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Type 2 Diabetes

(Diabetes Mellitus Type 2; Insulin-Resistant Diabetes; Diabetes, Type 2)

Definition  ^

Diabetes is a condition that makes it difficult for the body to use or store glucose. Glucose is a type of sugar that cells use for energy. It comes from food, and is also created in the liver. Glucose travels through the body in the blood. A hormone called insulin helps to moves the glucose from the blood into cells. Insulin also helps to move glucose into the liver for storage if there is more in the blood than the body needs.

Diabetes can lead to a buildup of glucose in the blood. This form of diabetes is the most common type in adults. Medication, lifestyle changes, and monitoring can help control blood glucose levels.

Causes  ^

Type 2 diabetes is often caused by a combination of factors. A main factor is that the body becomes resistant to insulin. This means there is insulin in the body, but the body cannot use it properly. Insulin resistance is often related to excess body fat. The body may also begin to make less insulin than is needed.

Risk Factors  ^

Type 2 diabetes is more common in people who are aged 45 years and older, but can develop in children. It is also common in younger people who are obese and belong to at-risk ethnic groups. Other factors that increase the chance of type 2 diabetes include:

  • Prediabetes—impaired glucose tolerance and impaired fasting glucose
  • Metabolic syndrome—combination of high cholesterol, high blood glucose, high blood pressure, and obesity with higher amounts of fat around the abdomen
  • Excess weight or obesity, especially if there are higher amounts of fat around the abdomen
  • Polycystic ovary syndrome
  • History of gestational diabetes, or having a baby that weighs over 9 pounds at birth
  • Poor diet—high intake of processed meats, fats, sugar-sweetened foods and beverages, and calories
  • Lack of exercise
  • Smoking
  • High blood pressure
  • Certain medications, such as glucocorticoids or thiazides

Symptoms  ^

Diabetes may be present for years before symptoms show.

Symptoms that may be caused by high blood sugar include:

  • Increased urination
  • Extreme thirst
  • Hunger
  • Fatigue
  • Blurry vision
  • Irritability

Symptoms caused by chronic hyperglycemia may include

  • Frequent or recurring infections
  • Poor wound healing
  • Numbness or tingling in the hands or feet
  • Problems with gums
  • Itching
  • Problems having an erection

Diagnosis  ^

You will be asked about your symptoms, family, and medical history. A physical exam will be done.

Diabetes is based on the results of blood tests. American Diabetes Association (ADA) diagnoses diabetes if you have one of the following:

  • Symptoms of diabetes and a random blood test with a blood sugar level greater than or equal to 200 mg/dL (11.1 mmol/L)
  • Fasting blood sugar test done after you have not eaten for 8 or more hours—showing blood sugar levels greater than or equal to 126 mg/dL (7 mmol/L) on two different days
  • Glucose tolerance test measures blood sugar 2 hours after you eat glucose—showing glucose levels greater than or equal to 200 mg/dL (11.1 mmol/L)
  • HbA1c level of 6.5% or higher—test that shows the average blood sugar control over the past 2-4 months

mg/dL = milligrams per deciliter of blood; mmol/L = millimole per liter of blood

You may also need blood tests to confirm diabetes is type 1 and not type 2. These may include:

  • Insulin level or C-peptide tests—to see how much insulin is being made by the pancreas
  • Tests that look for antibodies that are working against your pancreas

Treatment  ^

Treatment aims to keep blood glucose as close to normal as possible. This can help to prevent or delay complications.

Diet, exercise, and weight loss are recommended for all patients. Most patients will also begin medication.


Food and drinks have a direct effect on blood glucose levels. Eating healthy meals can help control blood glucose. It will also help with your heart health and overall health. Some basic tips include:

  • Follow a balanced meal plan. It should include carbohydrates, proteins, and fats.
  • Be aware of serving sizes. Measure food to help understand ideal serving size.
  • Having meals throughout the day can help avoid major changes in glucose levels. Do not skip meals. Plan meals and snacks through the day.
  • Eat plenty of vegetables and fiber.
  • Limit the amount of fat (especially saturated and trans fats) in foods.
  • Eat moderate amounts of protein and low-fat dairy products.
  • Carefully limit foods containing high concentrated sugar.
  • Keep a food intake record. Share the record with the dietitian or doctor. This will help to create an effective meal plan.

Weight Loss

In those who are overweight, weight loss will help the body use insulin better. Talk to the doctor about a healthy weight goal. A safe meal plan can be created.

To help with weight loss:


Physical activity can:

  • Make the body more sensitive to insulin
  • Help to reach and maintain a healthy weight
  • Lower the levels of fat in the blood
  • Reduce the risk of heart disease (a common complication of diabetes)

Aerobic exercise is any activity that increases heart rate. Resistance training helps build muscle strength. Both types of exercise help to improve long-term glucose control.

Aim for ≥ 150 minutes of physical activity each week. Talk to the doctor about an activity plan. Ask about any precautions that may be needed.


Non-insulin Glucose Lowering Medication

Medications other than insulin are typically used first to manage blood glucose levels.

Biguanides, usually metformin, are the first choice. They work by reducing the amount of glucose made by the body.

  • Medication taken by mouth may include:
    • Sulfonylureas or dipeptidyl peptidase IV (DPP-4) inhibitors to encourage the pancreas to make more insulin
    • Thiazolidinediones which sensitize the body to insulin so it works better at lower amounts
    • Starch blockers to decrease the amount of glucose absorbed into the blood
    • Sodium-glucose co-transporter 2 (SGLT-2) inhibitors to increase glucose excretion in urine
    • Bile acid binders
  • Medications given by injection may include:
    • Glucagon-like peptide-1 receptor agonists (incretin-mimetics) stimulate the pancreas to produce insulin and decrease appetite, which can assist with weight loss
    • Amylin analogs replace a protein of the pancreas that is low in people with type 2 diabetes


Insulin may be needed if:

  • The body does not make enough of its own insulin
  • Blood glucose levels cannot be controlled with lifestyle changes and other medications

Insulin is given through injections. There is one short-acting inhaled insulin which may be effective for select persons.

Blood Glucose Testing

Check the level of glucose in the blood with a blood glucose meter. Checking blood glucose levels during the day can help you stay on track. It will also help the doctor know if treatment is working. Keeping track of blood glucose levels is especially important for those taking insulin. Insulin can cause a very low level of blood glucose.

Regular testing may not be needed if diabetes is under control and insulin is not being taken. Talk with the doctor before stopping blood sugar monitoring.

An HbA1c test may also be done at the doctor's office. This is a measure of blood glucose control over a long period of time. Doctors advise that most people keep their HbA1c levels below 7%. Individual goals may be different. Keeping HbA1c in the goal range can help lower the chance of complications.


Depression can make good management more difficult. It also increases the risk of other complications. Feelings of sadness, hopelessness, and loss of interest in activities that last at least two weeks require a call to the doctor. Depression is treatable. Counseling can help better manage depression and diabetes.

Decreasing Risk of Complications  ^

Over a long period of time, high blood glucose levels can damage vital organs. The risk of complications increases with poor blood glucose control. Common complications include:

  • Retinopathy—damage to the blood vessels of the eye
  • Nephropathy—damage to kidneys which can lead to kidney failure
  • Neuropathy—damage to nerves that can cause a loss in sensation or loss in certain automatic functions
  • Diabetic foot ulcer—foot wounds that can be slow to heal

Diabetes can also increase the risk of heart disease.

Reaching your blood glucose and HbA1c levels is the first step to lowering the risk of these complications. Other steps that can help include:

  • Practice good foot care. Be on the lookout for any sores or irritated areas. Keep the feet dry and clean.
  • Get yearly eye exams.
  • Don't smoke. If you do, look for programs or products that can help you quit.
  • Keep track of moods. Be alert for signs of depression.
  • Plan medical visits as recommended.

Prevention  ^

To help reduce your chance of type 2 diabetes:

  • Participate in regular physical activity
  • Maintain a healthy weight
  • Drink alcohol only in moderation (2 drinks per day for a man, and 1 drink per day for a woman)
  • Eat a well-balanced diet with plenty of:
    • Whole grains
    • Nuts
    • Vegetables
    • Whole fruits

American Diabetes Association

National Diabetes Information Clearinghouse


Canadian Diabetes Association

Public Health Agency of Canada


American Association of Clinical Endocrinologists, American College of Endocrinology. Comprehensive Type 2 Diabetes Management Algorithm 2017. Endocr Pract. 2017 Feb;23(2):207-238.

American Diabetes Association Classification and Diagnosis of Diabetes of Diabetes Mellitus. Diabetes Care. 2015 Jan;38 Suppl:S8-S16.

Symptoms & Causes of Diabetes. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: Updated November 2016. Accessed August 25, 2017.

Diabetes. Centers for Disease Control and Prevention website. Available at: Updated July 25, 2016. Accessed August 25, 2017.

Diabetes mellitus type 2 in adults. EBSCO DynaMed Plus website. Available at: Updated August 25, 2017. Accessed August 25, 2017.

Diabetes mellitus type 2 in children and adolescents. EBSCO DynaMed Plus website. Available at: Updated July 18, 2017. Accessed August 25, 2017.

Dietary considerations for patients with type 2 diabetes. EBSCO DynaMed Plus website. Available at: Updated February 7, 2017. Accessed August 25, 2017.

Traina AN, Kane MP. Primer on pramlintide, an amylin analog. Diabetes Educ. 2011;37(3):426-431.

Type 2. American Diabetes Association website. Available at: Accessed September 19, 2017.

11/29/2006 DynaMed Plus Systematic Literature Surveillance. Lindstrom J, Ilanne-Parikka P, Peltonen M, Aunola S, Eriksson JG, Hemio K, et al. Sustained reduction in the incidence of type 2 diabetes by lifestyle intervention: follow-up of the Finnish Diabetes Prevention Study. Lancet. 2006;368:1673-1679.

9/19/2006 DynaMed Plus Systematic Literature Surveillance. Thomas DE, Elliott EJ, Naughton GA. Exercise for type 2 diabetes mellitus. Cochrane Database of Syst Rev. 2006;CD002968.

6/1/2007 DynaMed Plus Systematic Literature Surveillance. Nissen SE, Wolski K. Effect of rosiglitazone on the risk of myocardial infarction and death from cardiovascular causes. N Engl J Med. 2007;356(24):2457-2471.

7/13/2007 DynaMed Plus Systematic Literature Surveillance. Farmer A, Wade A, Goyder E, et al. Impact of self-monitoring of blood glucose in the management of patients with non-insulin treated diabetes: open parallel group randomised trial. BMJ. 2007;335(7611):132.

12/13/2007 DynaMed Plus Systematic Literature Surveillance. Milman U, Blum S, Shapira C, et al. Vitamin E supplementation reduces cardiovascular events in a subgroup of middle-aged individuals with both type 2 diabetes mellitus and the haptoglobin 2-2 genotype. A prospective double-blinded clinical trial. Arterioscler Thromb Vasc Biol. 2008;28(2):341-347.

2/28/2008 DynaMed Plus Systematic Literature Surveillance Davies MJ, Heller S, Skinner TC, et al. Effectiveness of the diabetes education and self management for ongoing and newly diagnosed (DESMOND) programme for people with newly diagnosed type 2 diabetes: cluster randomised controlled trial. BMJ. 2008;336(7642):491-495.

2/28/2008 DynaMed Plus Systematic Literature Surveillance Christian JG, Bessesen DH, Byers TE, Christian KK, Goldstein MG, Bock BC. Clinic-based support to help overweight patients with type 2 diabetes increase physical activity and lose weight. Arch Intern Med. 2008;168:141-146.

6/18/2008 DynaMed Plus Systematic Literature Surveillance ADVANCE Collaborative Group. Intensive blood glucose control and vascular outcomes in patients with type 2 diabetes. N Engl J Med. 2008;358:2560-2572.

2/24/2009 DynaMed Plus Systematic Literature Surveillance Liese AD, Weis KE, Schulz M, Tooze JA. Food intake patterns associated with incident type 2 diabetes: the Insulin Resistance Atherosclerosis Study. Diabetes Care. 2009;32:263-268.

5/11/2009 DynaMed Plus Systematic Literature Surveillance Loimaala A, Groundstroem K, Rinne M, et al. Effect of long-term endurance and strength training on metabolic control and arterial elasticity in patients with type 2 diabetes mellitus. Am J Cardiol. 2009;103:972-977.

8/19/2009 DynaMed Plus Systematic Literature Surveillance Li TY, Brennan AM, Wedick NM, Mantzoros C, Rifai N, Hu FB. Regular consumption of nuts is associated with a lower risk of cardiovascular disease in women with type 2 diabetes. J Nutr. 2009;139:1333-1338.

10/12/2009 DynaMed Plus Systematic Literature Surveillance Crandall JP, Polsky S, Howard AA, et al. Alcohol consumption and diabetes risk in the Diabetes Prevention Program. Am J Clin Nutr. 2009;90:595-601.

11/20/2009 DynaMed Plus Systematic Literature Surveillance Lund SS, Tarnow L, Frandsen M, et al. Combining insulin with metformin or an insulin secretagogue in non-obese patients with type 2 diabetes: 12 month, randomised, double blind trial. BMJ. 2009;339:b4324.

12/21/2009 DynaMed Plus Systematic Literature Surveillance Cappuccio FP, D'Elia L, Strazzullo P, Miller MA. Quantity and quality of sleep and incidence of type 2 diabetes: a systematic review and meta-analysis. Diabetes Care. 2010;33(2):414-420.

2/15/2010 DynaMed Plus Systematic Literature Surveillance American Diabetes Association. Standards of medical care in diabetes—2010. Diabetes Care. 2010;33(suppl 1:S11-61).

2/15/2010 DynaMed Plus Systematic Literature Surveillance American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care. 2010;33(suppl 1:S62-69).

7/2/2010 DynaMed Plus Systematic Literature Surveillance Micha R, Wallace SK, Mozaffarian D. Red and processed meat consumption and risk of incident coronary heart disease, stroke, and diabetes mellitus: a systematic review and meta-analysis. Circulation. 2010;121(21):2271-2283.

10/5/2010 DynaMed Plus Systematic Literature Surveillance Carter P, Gray LJ, Troughton J, Khunti K, Davies MJ. Fruit and vegetable intake and incidence of type 2 diabetes mellitus: systematic review and meta-analysis. BMJ. 2010;341:c4229.

1/4/2011 DynaMed Plus Systematic Literature Surveillance Pan A, Lucas M, Sun Q, et al. Bidirectional association between depression and type 2 diabetes mellitus in women. Arch Intern Med. 2010;170(21):1884-1891.

5/6/2011 DynaMed Plus Systematic Literature Surveillance Muraki I, Imamura F, Manson J, et al. Fruit consumption and risk of type 2 diabetes: results from three prospective longitudinal cohort studies. BMJ. 2013;347:f5001.

4/14/2014 DynaMed Plus Systematic Literature Surveillance Xi B, Li S, et al. Intake of fruit juice and incidence of type 2 diabetes: a systematic review and meta-analysis. PLoS One. 2014;9(3):e93471.

7/21/2014 DynaMed Plus Systematic Literature Surveillance Afshin A, Micha R, et al. Consumption of nuts and legumes and risk of incident ischemic heart disease, stroke, and diabetes: a systematic review and meta-analysis. Am J Clin Nutr. 2014;100(1):278-288.

9/11/2014 DynaMed Plus Systematic Literature Surveillance Tovote KA, Fleer J, Snippe E, et al. Individual mindfulness-based cognitive therapy and cognitive behavior therapy for treating depressive symptoms in patients with diabetes: results of a randomized controlled trial. Diabetes Care. 2014;37(9):2427-2434.

9/16/2014 DynaMed Plus Systematic Literature Surveillance Zhou D, Yu H, He F, et al. Nut consumption in relation to cardiovascular disease risk and type 2 diabetes: a systematic review and meta-analysis of prospective studies. Am J Clin Nutr. 2014;100(1):270-277.

12/14/2016 DynaMed Plus Systematic Literature Surveillance Shen HN, Yang CC, Chang YH, Lu CL, Li CY. Risk of diabetes mellitus after first-attack acute pancreatitis: a national population-based study. Am J Gastroenterol. 2015;110(12):1698-1706.

Last reviewed January 2018 by EBSCO Medical Review Board Michael Woods, MD, FAAP  Last Updated: 2/6/2018

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