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Diabetes Overview

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on July 31, 2020.

What is Diabetes?

Diabetes is a chronic, long-term disease marked by high levels of sugar in the blood. It can be caused by too little or no insulin (a hormone produced by the pancreas to regulate blood sugar, resistance to insulin (when cells in the body cannot effectively use insulin), or both of these issues.

Diabetes can lead to serious health complications including:

  • heart disease
  • blindness
  • kidney failure
  • lower-extremity amputations, such as a foot or lower leg.

Type 1 diabetes results from an absolute deficiency of insulin due to autoimmune beta cell destruction in the pancreas, while type 2 diabetes results from a progressive loss of insulin secretion coupled with insulin resistance.

Patients with type 1 diabetes require injected insulin, while patients with type 2 diabetes may be able to use oral agents only, or may need to combine injectable insulin with oral medications, too.

In the U.S., being overweight or obese is the most common modifiable risk factor for type 2 diabetes. With attention to diet, exercise, education, and medication treatment you can learn to control your diabetes, still enjoy many of the foods you love, and maintain your health over the long-term. Playing an active role in your treatment is key.

Do I Have Prediabetes?

Roughly 84 million people have prediabetes, when blood glucose levels are higher than normal but not yet high enough to be diagnosed as diabetes. Prediabetes is typically diagnosed when the A1C falls between 5.7% to 6.4%, the fasting plasma glucose (FPG) is 100 mg/dL to 125 mg/dL, or an oral glucose tolerance test (OGTT) is 140 mg/dL to 199 mg/dL. Long-term damage to the heart and circulatory system can still occur with prediabetes. Doctors may also refer to prediabetes as impaired glucose tolerance or impaired fasting glucose.

If caught early enough with screening, and combined with strong attention to diet, exercise, and lifestyle changes, prediabetes can be reversed.

Research shows that you can lower your risk for type 2 diabetes over half by:

  • Losing 7% of your body weight (roughly 15 pounds if you weigh 200 pounds).
  • Engaging in moderate exercise (such as brisk walking) 30 minutes a day, five days a week.

How Many People Have Diabetes?

  • Over 30 million people (9.4% of the population) have diabetes, with about 1.25 million American children and adults having type 1 diabetes.
  • The most common form of diabetes is type 2 diabetes, occurring in about 90% of patients with any form of diabetes.
  • About 7.2 million people with diabetes are currently undiagnosed.
  • The prevalence of diabetes is greater among older people. Among Americans aged 65 years or older, about 25% (1 in 4) have diabetes.
  • Rates of youth diagnosed with diabetes are rising. Close to 210,000 Americans under age 20 are estimated to have a diagnosis of diabetes.

What Are the U.S. Costs of Diabetes?

  • The American Diabetes Association (ADA) states that the total cost of prediabetes and diabetes in the U.S. is roughly $327 billion.
  • The cost in terms of life is significant also, with diabetes as the seventh leading cause of death in the United States, as reported by the ADA. This number may actually be underreported.

Treating diabetes has soared in the last decade; the average price of insulin nearly tripled between 2002 and 2013. However, more affordable generic insulin options are now becoming available. For example, using an online coupon, patients can pay one-third of the cost of a Humalog brand insulin if they choose the generic ("follow-on") insulin lispro.

Who Should Be Screened or Tested for Diabetes?


Screening in asymptomatic patients can occur at any age based on risk factors, such as obesity. All patients should be tested for type 2 diabetes starting at age 45 years. The test should be repeated every three years if the results are normal, dependent upon the risk status of the patient.

The ADA 2020 guidelines recommend testing for prediabetes and/or type 2 diabetes in asymptomatic  adults at any age with overweight or obesity (BMI ≥ 25 kg/m2 or ≥23 kg/m2 in Asian Americans) and who have one or more additional risk factors for diabetes, such as:

  • First-degree relative with diabetes
  • High-risk race/ethnicity (e.g., African American, Latino, Native American, Asian American, Pacific Islander)
  • History of CVD
  • Hypertension ($140/90 mmHg or on therapy for hypertension)
  • HDL cholesterol level < 35 mg/dL (0.90 mmol/L) and/or a triglyceride level > 250 mg/dL (2.82 mmol/L)
  • Women with polycystic ovary syndrome
  • Physical inactivity
  • Other clinical conditions associated with insulin resistance (e.g., severe obesity, acanthosis nigricans)

Screening should include the hemoglobin A1Cfasting blood sugar, or two-hour oral glucose tolerance test (OGTT). The OGTT is used more often for the diagnosis of gestational diabetes.

Patients with prediabetes (A1C ≥5.7%, impaired glucose tolerance or impaired fasting glucose) should be tested yearly.

Women who were previously diagnosed with gestational diabetes should have lifelong testing at least every 3 years.

Cardiovascular disease should be identified and treated in patients with prediabetes and type 2 diabetes.


In 2020, the American Diabetes Association (ADA) also recommends that testing for prediabetes or type 2 diabetes should be considered in children and adolescents (after the onset of puberty or after 10 years of age, whichever occurs earlier).

Test children who are overweight (BMI ≥85th percentile) or obese (BMI ≥95th percentile) and who have additional risk factors for diabetes, such as:

  • maternal gestational diabetes, family history (1st or 2nd degree relative)
  • certain race or ethnicity factors (Native American, African American, Latino, Asian American, Pacific Islander)
  • signs of insulin resistance (acanthosis nigricans, high blood pressure, high cholesterol or other lipids, polycystic ovary syndrome, or small-for-gestational age birth weight)

Pregnant Women

Women who are pregnant are routinely screened for gestational diabetes with an oral glucose tolerance test (OGTT).

  • The OGTT is a highly sugared drink given before blood testing so that the body's ability to process sugar (glucose) can be evaluated.
  • Screening may be recommended early in women who are obese or have a family history of diabetes.
  • If you have an average risk for gestational diabetes, screening usually occurs between 24 and 28 weeks of pregnancy.
  • Children of mothers who have a history gestational diabetes during that child's gestation period may have a greater risk of type 2 diabetes.
  • Women with a history of gestational diabetes should be tested every 3 years.

Types of Diabetes

There are three major types of diabetes:

  • Type 1 diabetes is usually diagnosed in childhood.
    • The beta cell of the pancreas makes little or no insulin, and daily injections of insulin are required to sustain life. Without proper daily management, medical emergencies can arise.
    • Type 1 diabetes was previously known as insulin-dependent diabetes mellitus (IDDM) or juvenile diabetes.
    • Type 1 is thought to be caused by genetic and environmental risk factors.
  • Type 2 diabetes is far more common than type 1 and makes up 90% or more of all cases of diabetes. However, many people with type 2 diabetes do not realize they have it.
    • Type 2 diabetes usually occurs in adulthood, although more cases are now occurring in children, primarily due to overweight and obesity issues.
    • Progressive loss of beta-cell insulin secretion combined with insulin resistance leads to this form of the  disease.
    • Type 2 diabetes is becoming more common due to the growing number of older Americans, increasing obesity, poor diets, and lack of exercise.
    • In the U.S., being overweight or obese is the most common modifiable risk factor for type 2 diabetes; however, not all patients with type 2 diabetes have weight problems. Genetic and environmental risk factors also play a role.
  • Gestational diabetes is high blood glucose that develops at the late stages of pregnancy in a woman who does not have diabetes.
    • Although gestational diabetes usually resolves after the baby is born, a woman may be at greater risk of developing type 2 diabetes later in life, and should be monitored.
    • Gestational diabetes can be caused by hormones or lack of insulin. Gestational diabetes may occur in roughly 5% of pregnant women, and being overweight or obese prior to becoming pregnant may be one factor.

Additional types of diabetes exist due to other causes, such as diseases of the pancreas from cystic fibrosis or pancreatitis, neonatal diabetes, or drug-induced diabetes (as with corticosteroids).

What causes diabetes?

  • During food metabolism and digestion glucose (sugar) enters the bloodstream to serve as a source of fuel for the body. An organ called the pancreas, which lies close to the stomach, makes insulin.
  • The role of insulin is to move glucose from the bloodstream into muscle, fat, and liver cells, where it can be used as fuel.
  • People with diabetes have high blood glucose because their pancreas does not make enough insulin or their muscle, fat, and liver cells do not respond to insulin normally (insulin resistance) -- or both.

Risk Factors for Diabetes

Type 1 diabetes risk factors

  • Genetics and family history
  • The presence of autoantibodies in which the insulin-producing cells are attacked.
  • Environmental factors or possible virus exposure.
  • Caucasian race, and Finnish and Swedish people also seem to have a higher risk for Type 1 diabetes.

Type 2 diabetes risk factors

  • Overweight (body mass index [BMI] ≥25 kg/m2) or obese (BMI ≥30 kg/m2).
  • A parent, brother, or sister with diabetes (family history).
  • Age greater than 45 years.
  • Certain ethnic groups (particularly African-Americans, Latinos, Native American, Asian American, Pacific Islander).
  • A history of gestational diabetes.
  • A history of polycystic ovary syndrome (PCOS).
  • A1C ≥5.7%, impaired glucose tolerance (IGT) or impaired fasting glucose (IFG).
  • High blood pressure over 140/90 mm/Hg or taking blood pressure treatment.
  • A history of vascular disease.
  • High blood levels of triglycerides (a type of fat molecule) >250 mg/dL.
  • Low HDL cholesterol <35 mg/dL (“good” cholesterol).
  • Conditions suggestive of insulin resistance i.e., (acanthosis nigricans, severe obesity).
  • A sedentary, inactive lifestyle.

Gestational diabetes risk factors

  • Age older than 25 years.
  • Personal history of gestational diabetes or prediabetes.
  • Close family member (such as a parent, brother, sister) with type 2 diabetes.
  • Currently overweight or obese.
  • Women who are African American, Latino, American Indian or Asian are more likely to develop gestational diabetes.
  • Polycystic ovary syndrome (PCOS).

As previously mentioned, the American Diabetes Association (ADA) 2020 Guidelines recommend that all adults be screened for diabetes at least every 3 years. A person at high risk should be screened more often.

What Are the Symptoms of Diabetes?

Symptoms of type 1 diabetes:

  • Increased thirst
  • Increased urination
  • Weight loss in spite of increased appetite
  • Fatigue
  • Nausea
  • Vomiting

Symptoms of type 2 diabetes:

  • Increased thirst
  • Increased urination
  • Increased appetite
  • Fatigue
  • Blurred vision
  • Slow-healing infections
  • Impotence in men

High blood levels of glucose can cause many of these of symptoms, but because type 2 diabetes develops slowly, some people with high blood sugar experience no symptoms at all. That’s one reason why screening is so important.

Symptoms of gestational diabetes:

  • Usually no noticeable symptoms
  • Rarely may have increased thirst or urination
  • Typically you will find out that you have gestational diabetes through a routine glucose challenge test given between 24 and 28 weeks of pregnancy.

What Tests Are Used to Diagnose Diabetes?

A urinalysis may be used to look for glucose and ketones from the breakdown of fat. However, a urine test alone does not diagnose diabetes. The following blood glucose tests (Table 1) are used to diagnose diabetes:

  • Hemoglobin A1C test (HbA1C): The A1C test measures the average blood glucose for the last 2 to 3 months. An A1C level of 6.5% indicates a diagnosis of diabetes, prediabetes is between 5.7% and 6.4%, and normal levels are below 5.7%. Some patients with hemoglobin disorders or sickle cell traits may have skewed A1C results, per 2018 ADA guidelines.
  • Fasting blood glucose level (FBG): Diabetes is diagnosed if higher than 126 mg/dL (7.0 mmol/L) on two occasions. Levels between 100 mg/dL and 125 mg/dL (5. 5 mmol/L and 7.0 mmol/L) are referred to as impaired fasting glucose or prediabetes. This test is taken after you have not eaten for at least 8 hours (fasting).
  • Oral glucose tolerance test (OGTT): Diabetes is diagnosed if your glucose level is higher than 200 mg/dL (11.1 mmol/L) after 2 hours following the consumption of a sugary drink known as the oral glucose tolerance test (OGTT). This test is used for the diagnosis of gestational diabetes.
  • Random (non-fasting) blood glucose level (RGT): This is checked any time of the day when you have severe signs of high blood sugar. Diabetes is suspected if higher than 200 mg/dL (11.1 mmol/L) and accompanied by the classic symptoms of increased thirst, urination, fatigue, hunger and weight loss. This test must be confirmed with a fasting blood glucose test (FBG) or HbA1c.

In the absence of a definite clinical diagnosis of high blood sugar (hyperglycemia), repeat testing should be performed for confirmation. If your blood sugar is very high, your doctor may not require a second test. Patients falling on the margins of the numbers should have repeat testing in 3 to 6 months.

Table 1: ADA 2020 Diagnostic Criteria for Prediabetes / Diabetes Diagnosis

  Prediabetes Diabetes
A1C 5.7%-6.4% ≥6.5%
FPG 100-125 mg/dL ≥126 mg/dL
OGTT 140-199 mg/dL ≥200 mg/dL
RGT N/A ≥200 mg/dL*

*only diagnostic with overt signs of hyperglycemia or hyperglycemia crisis

Prediabetes puts you at a higher risk for developing type 2 diabetes and heart disease.

Patients with type 1 diabetes usually develop symptoms over a short period of time, and the condition is often diagnosed in an emergency setting. 


In addition to having high blood sugar levels, acutely ill people with type 1 diabetes have high levels of ketones.

  • Ketones are produced by the breakdown of fat and muscle when glucose is not available for energy, and they are toxic at high levels. Ketones in the blood cause a condition called "acidosis" (low blood pH) or diabetic ketoacidosis.
  • Urine testing detects both glucose and ketones in the urine. Blood glucose levels are also high which lead to dehydration.
  • Ketoacidosis is dangerous and potentially fatal if not treated. Ketoacidosis is uncommon in those with type 2 diabetes.

Diabetes Treatment

Lifestyle changes are the cornerstone of diabetes management for all patients. In addition to medication, achieving goals for weight management and diet, physical activity, smoking cessation, and moderate alcohol use is important for diabetes control.

What are the signs of low blood sugar? You need to learn how to recognize the signs of low blood sugar (hypoglycemia) as it can occur when taking many diabetes treatments and can be dangerous.

Common symptoms include:

  • Headache
  • Hunger
  • Shakiness
  • Weakness
  • Sweating
  • Irritability
  • Difficulty with concentrating

Always keep a source of sugar close by to consume if you have symptoms of low blood sugar. Sources of sugar include orange juice, glucose gel, candy or an injection of glucagon (available from your doctor).

What Medications Are Used for Type 1 Diabetes?


Medications to treat diabetes are used to control blood sugar, these include:

  • insulin injections
  • inhaled insulin
  • other classes of oral or injectable medications.

People with type 1 diabetes cannot make their own insulin, so daily insulin injections or inhalations are required. People with type 2 diabetes make insulin but cannot use it effectively; however, insulin is still used as an effective add-on treatment in many patients with type 2 diabetes.

Insulin is usually given by injections that are required one to four times per day. Some people use an insulin pump, which is worn at all times and delivers a steady flow of insulin throughout the day.

Insulin preparations differ in how quickly they start to work and how long they remain active. Sometimes different types of insulin are mixed together in a single injection. The types of insulin to use, the doses required, and the number of daily injections are chosen by a healthcare professional trained to provide diabetes care.

People who need insulin are taught to give themselves injections by their diabetes educators. Special insulin pens are also available for some insulins that prevent the need for pulling up insulin with a needle into a syringe. The insulin is stored in the pen with attached needles.

View available insulin products: Diabetes Treatment

Follow-On Insulins

These insulins have the same active ingredients as the original reference product, but cannot be substituted for each other at the pharmacy without your doctor's approval via a prescription. A "follow on" insulin is approved via an abbreviated FDA process. 

In Europe, "follow-on" insulins are considered to be biosimilar, but in the U.S. this is not the case. Because insulin is regulated under the Food, Drug, and Cosmetic (FDC) Act, and not the Public Health Services (PHS) Act, it is not possible to have a biosimilar insulin in the United States.

Afrezza: An Inhaled Insulin

Insulin is not available in oral tablet form, although an orally inhaled insulin product called Afrezza was approved in 2014.

Afrezza is an ultra rapid-acting inhaled insulin that is administered with meals to improve blood sugar control in adult diabetics. Insulin is usually is delivered by injections that are required one to four times per day, so this may be good option for patients who prefer not to have multiple injections throughout the day.

What Medications Are Used for Type 2 Diabetes?

If the combination of a healthy diet and physical activity has not adequately controlled your blood sugar levels in type 2 diabetes, the addition of a medication can be helpful. Unlike type 1 diabetes, type 2 diabetes may respond to treatment with exercise, diet, and/or oral or injectable medications other than insulin. Many antidiabetic combination agents are available, as well.

  • Most patients with type 2 diabetes will require more than one medication for good blood sugar control within three years of starting their first medication.
  • The ADA recommends the use of insulin in patients who do not reach their blood sugar goals with the use of two oral agents. Insulin may be required earlier in newly diagnosed patients with A1C levels ≥10% and/or blood glucose levels ≥300 mg/dL.
  • As outlined in the ADA Pharmacologic Therapy for Type 2 Diabetes: Standards of Medical Care in Diabetes—2020, treatment selection should be patient-centered, considering drug effectiveness, risk of low blood sugar, heart disease risk factors, weight, side effects, kidney impairment, cost, and patient preferences, including for oral or injected medications.

Is Metformin the First Drug Used in Type 2 Diabetes?

Metformin (brand name examples: Glumetza, Riomet; generics), in the class biguanides, is the recommended first-line oral treatment for type 2 diabetes by the 2020 American Diabetes Association (ADA) guidelines.

Metformin reduces high blood sugar by decreasing sugar production (liver gluconeogenesis), lowering the breakdown of glycogen to glucose-1-phosphate and glucose (glycogenolysis), and increasing insulin sensitivity.

  • Almost everyone who is newly diagnosed with type 2 diabetes will start with this medication. Metformin is a preferred initial drug therapy because it rarely leads to weight gain or hypoglycemia (low blood sugar), is available generically and therefore is cost- effective, and has been shown to have a positive effect on LDL cholesterol. Some patients who initially present with excessively high blood sugar may require short-term insulin.
  • Metformin is taken orally as pill, usually 1 to 3 times per day (with meals to lower stomach upset). Extended-release products can be used once-a-day if tolerated.
  • Stomach side effects such as nausea, flatulence and diarrhea can be common, but improve if taken with a meal.
  • Long-term use of metformin may result in a vitamin B12 deficiency, and periodic monitoring may be warranted, especially in patients with anemia or peripheral neuropathy.
  • Insulin is also an option as a first-line drug treatment for type 2 diabetes, especially with higher A1C, although hypoglycemia and weight gain can be issues. 

Adding a Second Medication in Type 2 Diabetes

Patients may require a second medication if their blood sugar is not fully controlled after 2 or 3 months with adequate doses of metformin. Earlier combination therapy may be appropriate in some patients. The choice of second medication depends upon blood sugar control (A1C levels), patient history, and cost concerns. Oral and injectable medications are available, including insulin.


Generic Name Brand Name Examples
chlorpropamide Diabinese (brand discontinued)
glimepiride Amaryl
glipizide Glucotrol, Glucotrol XL
glyburide DiaBeta, Glynase, Micronase (brand discontinued)
tolazamide Tolinase (brand discontinued)
tolbutamide Orinase, Tol-Tab (brands discontinued)

Sulfonylurea Combinations

Generic Name Brand Name Examples
glimepiride and pioglitazone Duetact
glimepiride and rosiglitazone Avandaryl (brand discontinued)
glipizide and metformin Metaglip (brand discontinued)
glyburide and metformin Glucovance (brand discontinued)
  • Sulfonylureas might be selected first as an add-on agent if blood sugar is not well-controlled with metformin and lifestyle changes. Sulfonylureas act to increase insulin production by the pancreas (insulin secretagogues).
  • Shorter-acting sulfonylureas are agents such as glimepiride (Amaryl) or glipizide. Glyburide can lead to significant low blood sugar (hypoglycemia) and may not be the best first-choice sulfonylurea, especially in older individuals. Glimepiride or glipizide may also be a better choice in kidney impaired patients.
  • Dosing is usually once or twice a day by mouth.
  • Sulfonylureas can also be used as a single therapy (monotherapy) in patients who cannot tolerate metformin side effects. Shorter-acting agents are usually preferred.
  • Most patients with sulfonamide allergies are still able to tolerate the use of sulfonylureas without problems.


Generic Name Brand Name
nateglinide Starlix (brand discontinued)
repaglinide Prandin (brand discontinued)
  • Repaglinide and nateglinide are oral medications in the drug class known as meglitinides. They act like the sulfonylureas to increase insulin production from the pancreas. They can be used in place of the sulfonylureas, if needed. Combination agents include repaglinide and metformin (PrandiMet).
  • Meglitinides are taken by mouth with each meal 2 to 4 times a day, as determined by your blood sugar response.
  • Like sulfonylureas, these agents may also lead to low blood sugar (hypoglycemia) as a side effect.
  • Respiratory symptoms like a cold, diarrhea, constipation, headache and joint pain are other common side effects.

Alpha-Glucosidase Inhibitors

Generic Name Brand Name
acarbose Precose (brand discontinued)
miglitol Glyset
  • Alpha-glucosidase inhibitors work by inhibiting intestinal enzymes that digest carbohydrates to delay glucose absorption. This results in a smaller and slower rise in blood sugar levels following meals and throughout the day.
  • They can be added to other treatments if needed, but are not as effective as metformin or sulfonylyureas in lowering blood glucose.
  • These drugs are taken three times daily at the start (with the first bite) of each main meal.
  • Common side effects include: abdominal pain, diarrhea, and flatulence (gas) which is worse with higher doses. Start treatment with lower doses and increase slowly to lessen stomach side effects.

Thiazolidinediones (glitazones)

Generic Name Brand Name
pioglitazone Actos
rosiglitazone Avandia

Thiazolidinedione Combinations

Generic Name Brand Name
alogliptin and pioglitazone Oseni
glimepiride and pioglitazone Duetact
glimepiride and rosiglitazone Avandaryl (brand discontinued)
metformin and pioglitazone Actoplus Met, Actoplus Met XR (brand discontinued)
metformin and rosiglitazone Avandamet (brand discontinued)
  • Thiazolidinediones (glitazones) work by boosting the efficiency of glucose utilization via actions on muscle, fat and liver to increase insulin sensitivity.
  • Thiazolidinediones are given orally either once or twice daily. They do not normally cause low blood sugar.
  • They can be used as first or second-line agents in combination, but insulin or a short-acting sulfonylurea may be preferred due to side effects such as weight gain, edema, heart failure, and bone fractures.
  • Other possible serious side effects like bladder cancer, macular edema, and heart attack have also been reported.

Dipeptidyl Peptidase 4 Inhibitors (DPP-4 Inhibitors)

Generic Name Brand Name
sitagliptin Januvia
saxagliptin Onglyza
linagliptin Tradjenta
alogliptin Nesina

DPP-4 Inhibitor Combinations

Generic Name Brand Name
sitagliptin and simvastatin Juvisync (brand discontinued)
sitagliptin and ertugliflozin Steglujan
sitagliptin and metformin Janumet, Janumet XR
saxagliptin and dapagliflozin Qtern, Qternmet XR
saxagliptin and metformin Kombiglyze XR
linagliptin and metformin Jentadueto, Jentadueto XR
linagliptin and empagliflozin Glyxambi
alogliptin and metformin Kazano
alogliptin and pioglitazone Oseni
  • DPP-4 inhibitors (dipeptidyl peptidase 4 inhibitors or gliptins) are oral medications for type 2 diabetes. They might be combined with other medications such as metformin or an SGLT-2 inhibitor for added blood sugar control. One product (Juvisync) is combined with simvastatin, an agent used to lower blood cholesterol.
  • DPP-4 inhibitors work by blocking the action of dipeptidyl peptidase-4 (DPP-4), an enzyme which destroys the hormone incretin. Incretins help the body to make and release more insulin when needed and reduce unneeded liver production of glucose.
  • DPP-4 inhibitors improve blood glucose and reduce both fasting and postprandial (after a meal) blood glucose levels without normally causing weight gain. They do not usually cause hypoglycemia (low blood sugar levels) unless they are combined with other therapies that cause hypoglycemia. They are dosed orally once a day.
  • Possible side effects of DPP-4 inhibitors include: rare severe allergic reactions, rare pancreatitis (inflammation of the pancreas), cold-like symptoms, headache, joint pain, stomach pain, nausea, and diarrhea.

SGLT-2 Inhibitors

Generic Name Brand Name
canagliflozin Invokana
dapagliflozin Farxiga
ertugliflozin Steglatro
empagliflozin Jardiance

SGLT-2 Inhibitor Combinations

Generic Name Brand Name
dapagliflozin and metformin Xigduo XR
dapagliflozin and saxagliptin Qtern
canagliflozin and metformin Invokamet, Invokamet XR
ertugliflozin and sitagliptin Steglujan
ertugliflozin and metformin Segluromet
empagliflozin and linagliptin Glyxambi
empagliflozin and metformin Synjardy, Synjardy XR
  • SGLT-2 inhibitors (sodium-glucose cotransporter-2 inhibitors) block proteins in the kidneys and increases urine glucose (sugar) excretion leading to lower blood sugar (glucose) levels.
  • These agents are not used as a first-line treatment, but may improve weight loss and blood pressure, and can be used in combination with other agents. They do not cause low blood sugar levels. Some are also labeled for cardiovascular risk reduction.
  • They are given by mouth typically once a day with or without food.
  • Side effects, such as genital yeast infections, genitourinary tract infections (men and women), kidney impairment, low blood pressure, and elevated potassium levels (hyperkalemia) may occur.
  • A boxed warning exists on canagliflozin (Invokana, Invokamet XR) labeling due to elevated risk of limb amputation and bone fracture.
  • Certain agents are recommended based on risk reduction of major cardiovascular events in patients with established heart disease (i.e., Farxiga, Invokana, Jardiance).

GLP-1 Agonists (Incretin Mimetics)

Generic Name Brand Name
albiglutide Tanzeum
exenatide Byetta, Bydureon
dulaglutide Trulicity
lixisenatide Adlyxin
semaglutide Ozempic, Rybelsus (oral form)
liraglutide Victoza

GLP-1 Agonist Combinations

Generic Name Brand Name
liraglutide and insulin degludec Xultophy
lixisenatide and insulin glargine Soliqua 100/33
  • GLP-1 (glucagon-like peptide-1) agonists (may also be called incretin mimetics) are subcutaneously injected agents that work by activating GLP-1 receptors and increasing insulin release when needed. In 2017, the 1st oral GLP-1 agent, Rybelus (semaglutide), was approved.
    • They also suppress appetite and inhibit glucagon secretion to lower glucose production by the liver when it’s not needed.
    • They lower the rate at which the stomach digests food (gastric emptying) which can help to reduce your appetite.
  • The GLP-1 agonists are not used as first line agents but may be used if blood sugar is not controlled with other medications, and to help with weight loss. They do not cause low blood sugar.
  • These drugs are given by subcutaneous (under the skin) injection or orally; some products are used daily and some are used weekly. The oral product, Rybelsus, is given once daily.
  • Common side effects can include nausea, vomiting, diarrhea and injection site reactions. Pancreatitis and thyroid cell cancer has been rarely reported. Patients with impaired kidney function may need to stop the medication.
  • Some agents (i.e., Ozempic, Trulicity, Victoza) are recommended based on risk reduction of major cardiovascular events in patients with established heart disease.

Amylin Analog

Generic Name Brand Name
Pramlintide Symlin (SymlinPen 120, SymlinPen 60)

Pramlintide, an amylin analog, is an injectable medication for adults with type 1 and type 2 diabetes to help control blood sugar. It works in three different ways:

  • Slows down food movement through the intestines, which keeps blood sugar (glucose) levels from rising too quickly.
  • Lowers the amount of glucose made by the liver.
  • Produces a feeling of fullness to control appetite and decrease food intake.

Pramlintide should only be used by people with type 1 or type 2 diabetes who already use their insulin as prescribed but still need better blood sugar control. Pramlintide is always used alongside insulin to help lower blood sugar during the 3 hours after meals. It might be considered for patients who are inadequately controlled on mealtime insulin and experience gain weight gain.

However, even when pramlintide is carefully added to mealtime insulin therapy, blood sugars may drop too low, especially in patients with type 1 diabetes. If this low blood sugar (severe hypoglycemia) happens, it is generally seen within 3 hours after a pramlintide injection.

Never mix pramlintide and insulin. You must use different syringes for pramlintide and insulin because insulin can affect pramlintide when the two are mixed together.

Do Patients With Diabetes Need to Take Heart Medications?

  • Blood thinners such as aspirin or clopidogrel (Plavix) may be started in people with type 2 diabetes at higher risk for cardiovascular events such as stroke or heart attack.
  • Other medications such as blood pressure control or high cholesterol treatments may be needed, as well.
  • Angiotensin converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs) will be started in many diabetic patients, especially those with protein in their urine and high blood pressure, to help protect the kidneys and other organs.
  • Pregnant women should not take ACE inhibitors or ARBs.

Which Diabetes Drugs Have a Cardiovascular Benefit?

If additional therapy for type 2 diabetes is needed after lifestyle management and metformin use in patients with established heart disease. Drugs from both the SGLT-2 Inhibitor and GLP-1 Agonist groups have shown cardiovascular benefit.

  • Dulaglutide (Trulicity), liraglutide (Victoza), empagliflozin (Jardiance), semglutide (Ozempic) are indicated to reduce major cardiovascular events (stroke, heart attack) and/or cardiovascular mortality (death). The oral form of semaglutide (Rybelsus) does not yet have the cardiovascular risk reduction indication.
  • Canagliflozin (Invokana) can be selected based on a reduction in major cardiovascular events and reduction in the risk of end-stage kidney disease (ESKD), doubling of serum creatinine, cardiovascular (CV) death, and hospitalization for heart failure in adults with type 2 diabetes mellitus and diabetic nephropathy (kidney disease).
  • Dapagliflozin (Farxiga) has been shown to reduce the risk of hospitalization for heart failure in adults with type 2 diabetes mellitus and established cardiovascular disease (CVD) or multiple cardiovascular (CV) risk factors.

Atherosclerotic cardiovascular heart disease (ASCVD) is defined as coronary heart disease, cerebrovascular disease, or peripheral artery disease.

In the ADA guidelines, these drugs are recommended as first-choice agents in patients with established ASCVD, after considering patient and drug-specific factors. These three agents may also have a benefit in the progression of diabetic kidney disease (diabetic nephropathy).

Can You Stop Type 2 Diabetes Medications?

Some people with type 2 diabetes find they no longer need medication if they lose weight and increase activity. When their ideal weight is reached, their own insulin and a careful diet may control their blood glucose levels.

Even a 10 to 15% weight loss in some diabetic patients can drastically lower blood sugar. A patient must be highly motivated and adhere to their diet and exercise regimen to maintain their blood sugar levels and stay off of medication. However, you should only stop taking your diabetes medication under the supervision of your diabetes healthcare provider.

How Do I Test My Blood Sugar?

Self-monitoring of blood glucose (SMBG) is done by checking the glucose content of a drop of blood in a blood glucose meter. Regular testing tells you how well diet, medication, and exercise are working together to control your diabetes. SMBG is especially important for patients using insulin to help avoid high and low blood sugar. Continuous glucose monitoring (CGM) has also been shown to be as safe and effective as SMBG. 

The results of the test can be used to adjust meals, activity, or medications to keep blood sugar levels in an appropriate range. Testing provides valuable information for the health care provider and identifies high and low blood sugar levels before serious problems develop.

The American Diabetes Association recommends that pre-meal blood sugar levels fall in the range of 80 to 130 mg/dL and peak post-meal blood levels are ≤180 mg/dL (1 to 2 hours after the beginning of a meal). Your doctor may adjust this depending on your circumstances.

Your doctor will probably check your hemoglobin A1c (HbA1c) level at least twice a year if you are meeting treatment goals.

  • The HbA1c is a measure of average blood glucose during the previous two to three months.
  • It is a very helpful way to monitor a patient's overall response to diabetes treatment over time.
  • According to the ADA, people with diabetes should try to keep their A1c below 7%, although your doctor may adjust this based on your specific circumstances.

In 2018, the A1C targets from the ADA came under fire. For most adults, the ADA has recommended a target A1C of below 7%, which can be altered based on individual circumstances. But in March 2018, the American College of Physicians (ACP) relaxed these targets, saying the A1C should be between 7% and 8% for most adults with type 2 diabetes. They recommend adjusting treatment to keep A1C's from going below 6.5%, and avoiding target A1C levels in patients over 80 years, and those who live in a nursing home or those with chronic health conditions. Instead, they suggest minimizing high blood sugar in these groups.

What are Ketones?

Ketone testing is another test that is used in type 1 diabetes. Ketones build up in the blood when there is not enough insulin in people with type 1 diabetes, eventually "spilling over" into the urine. The ketone test is done on a urine sample. High levels of blood ketones may result in a serious condition called diabetic ketoacidosis. Ketone testing is usually done at the following times:

  • When the blood sugar is higher than 240 mg/dL
  • During acute illness (for example, pneumonia, heart attack, or stroke)
  • When nausea or vomiting occur
  • During pregnancy

Ketoacidosis is rare in people with type 2 diabetes.

Hyperosmolar Hyperglycemic Nonketotic Syndrome (HHNS)

Another complication that can be avoided by checking the blood sugar level is Hyperosmolar Hyperglycemic Nonketotic Syndrome (HHNS). HHNS is a serious condition usually seen in older persons with type 2 diabetes, although it can occur in type 1 patients also.

HHNS is usually brought on by an illness or infection. HHNS may occur gradually, but only occurs when diabetes is uncontrolled, and may take days or even weeks to develop. The best way to avoid HHNS is to check your blood sugar regularly. Be aware of the symptoms of HHNS that include:

  • Blood sugar level over 600 mg/dL
  • Dry mouth
  • Excessive urination
  • Dark colored urine
  • Extreme thirst
  • Warm, dry skin that does not sweat
  • High fever (over 101 degrees Fahrenheit)
  • Sleepiness or confusion
  • Loss of vision
  • Hallucinations (seeing or hearing things that are not there)
  • Weakness on one side of the body

Should People With Type 2 Diabetes Exercise?

Regular exercise and lifestyle changes are especially important for people with diabetes. It helps with blood sugar control, weight loss, and high blood pressure. People with diabetes who exercise are less likely to experience a heart attack or stroke than diabetics who do not exercise regularly. You should be evaluated by your physician before starting an exercise program.

Here are some exercise tips:

  • Choose an enjoyable physical activity that is appropriate for your current fitness level.
  • Exercise every day, and at the same time of day, if possible.
  • Monitor blood glucose levels before and after exercise.
  • Carry food that contains a fast-acting carbohydrate in case you become hypoglycemic (low blood sugar) during or after exercise.
  • Carry a diabetes identification card and a mobile phone in case of emergency.
  • Drink extra fluids that do not contain sugar before, during, and after exercise.
  • Changes in exercise intensity or duration may require changes in diet or medication dose to keep blood sugar levels from going too high or low.

Diabetes and Your Feet

Foot care is very important in people with diabetes due to the likelihood of damage to blood vessels and nerves and a decreased ability to fight infection. Problems with blood flow and damage to nerves may cause an injury to the foot to go unnoticed until infection develops. Death of skin and other tissue can occur.

If left untreated, the affected foot may need to be amputated. Diabetes is the most common condition leading to amputations.

To prevent injury to the feet, people with diabetes should adopt a daily routine of checking and caring for the feet as follows:

  • Check your feet every day, and report sores or changes and signs of infection.
  • Wash your feet every day with lukewarm water and mild soap, and dry them thoroughly.
  • Soften dry skin with lotion or petroleum jelly.
  • Protect feet with comfortable, well-fitting shoes.
  • Exercise daily to promote good circulation.
  • See a podiatrist for foot problems or to have corns or calluses removed.
  • Remove shoes and socks during a visit to your health care provider and remind him or her to examine your feet.
  • Stop smoking, which hinders blood flow to the feet.

Studies on Blood Sugar Control in Type 2 Diabetes

The risks of long-term complications from diabetes can be reduced.

The Diabetes Control and Complications Trial (DCCT) studied the effects of tight blood sugar control on complications in type 1 diabetes. Patients treated for tight blood glucose control had an average HbA1c of approximately 7%, while patients treated less aggressively had an average HbA1c of about 9%. At the end of the study, the tight blood glucose group had dramatically fewer cases of kidney disease, eye disease, and nervous system disease than the less aggressively treated patients.

In the United Kingdom Prospective Diabetes Study (UKPDS), researchers followed nearly 4,000 people with type 2 diabetes for 10 years. The study monitored how tight control of blood glucose (HbA1c of 7% or less) and blood pressure (less than 144 over less than 82) could protect a person from the long-term complications of diabetes.

The UKPDS study found dramatically lower rates of kidney, eye, and nervous system complications in patients with tight control of blood glucose. In addition, there was a significant drop in all diabetes-related deaths, including lower risks of heart attack and stroke. Tight control of blood pressure was also found to lower the risks of heart disease and stroke.

The results of the DCCT and the UKPDS dramatically demonstrate that with good blood glucose and blood pressure control, many of the complications of diabetes can be prevented.

Possible Complications of Diabetes

Emergency complications include diabetic hyperglycemic hyperosmolar coma.

Long-term diabetes complications include:

  • Diabetic retinopathy
  • Diabetic nephropathy
  • Diabetic neuropathy
  • Peripheral vascular disease
  • Hyperlipidemia, hypertension, atherosclerosis, and coronary artery disease

When to Contact a Medical Professional

Go to the emergency room or call the local emergency number (such as 911) if symptoms of ketoacidosis occur:

  • Increased thirst and urination
  • Nausea
  • Deep and rapid breathing
  • Abdominal pain
  • Sweet-smelling breath
  • Loss of consciousness

Go to the emergency room or call the local emergency number if symptoms of extremely low blood sugar (hypoglycemic coma or severe insulin reaction) occur:

  • Weakness
  • Drowsiness
  • Headache
  • Confusion
  • Dizziness
  • Double vision
  • Lack of coordination
  • Convulsions or unconsciousness

Can Diabetes Be Cured?

There is no cure for diabetes. The immediate goals are to stabilize your blood sugar and eliminate the symptoms of high blood sugar. The long-term goals of treatment are to prolong life, relieve symptoms, and prevent long-term complications such as heart disease, amputations, and kidney failure.

How Can I Prevent Diabetes?

Type 1

Currently there is no way to prevent type 1 diabetes.

Maintaining an ideal body weight and an active lifestyle may prevent the onset of type 2 diabetes.

Type 2

Research shows that you can lower your risk for type 2 diabetes by over one-half by:

  • Losing weight if needed (roughly 7%, or about 15 pounds if you weigh 200 pounds)
  • Engaging in moderate exercise (such as brisk walking) 30 minutes a day, five days a week.
  • Maintaining a healthy, low-fat diet.

If recommended by your doctor, start the use of metformin if you have prediabetes, and a BMI ≥35 kg/m2, age <60 years, and women with a history of gestational diabetes. The use of metformin for prevention of type 2 diabetes is “off-label” but has been shown in research to be effective in some patients.

The American Diabetes Association (ADA) recommends that all adults be screened for diabetes at least once every three years. A person with risk factors should be screened more often.

Is Weight-Loss Surgery Effective in Diabetics?

Weight loss surgery may be an option for patients with a BMI over 35 kg/m2 and type 2 diabetes. After surgery, patients will need lifelong lifestyle support and medical monitoring. Improvements in blood pressure, blood sugar, and cholesterol levels have all been documented for these patients, as well as a longer life span.

However, a study published in the Journal of the American Medical Association (JAMA) found that among 120 type 2 diabetic patients who received weight-loss surgery, their ability to control their triple endpoint -- blood sugar, blood pressure and cholesterol levels -- diminished over time. The drop in achievement of the triple endpoint target among the gastric bypass group was from 50% at one year to 23% at five years. But the study did find lower mortality rates by up to 50% in the obese patient who had the bypass surgery, compared to matched obese patients who continue with usual care.

Support Groups for Diabetes

Successfully controlling your diabetes takes a daily effort. Your doctor should always be your top healthcare advisor. However, you may be able to share your concerns, learn useful tips, and gain emotional strength by interacting with others who share your same condition and have the same questions, especially with such complicated conditions as diabetes.

Consider joining the Type 1 Diabetes or Type 2 Diabetes Support Groups to voice your opinion, ask questions, and keep up with the recent news on diabetes.

See Also


Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.