Understanding the Basics of Diabetes


Diabetes is a condition in which the body either does not produce enough insulin or is not able to use the insulin effectively. As a result, the glucose in the blood (often called blood sugar) becomes too high.


There are 29.1 million Americans who have the condition, of which 8 million do not know that they have diabetes. The number of people with diabetes has increased along with the number of people who are overweight or obese. Diabetes is more common among minorities such as blacks, Hispanics, Asian Americans and Native Americans. People can get diabetes at any age, but the risk increases as we get older. It is estimated that in 2014, nearly 25 percent of people over the age of 65 have diabetes. There are three main types of diabetes: type 1, type 2 and gestational (je-sta-shen-al) diabetes.


Type 1 diabetes (previously also known as juvenile diabetes or insulin-dependent diabetes)

Type 1 diabetes develops because the cells that produce insulin (beta cells) are destroyed by an immune process, and the body, therefore, is unable to produce sufficient amounts of insulin. Only about five to 10 percent of people with diabetes have type 1 diabetes. Type 1 diabetes typically occurs in children and young adults, but may occur at any age. So even if you are 90 years of age, you can develop juvenile diabetes!

Type 2 diabetes (previously also known as adult onset diabetes or non-insulin dependent diabetes)

Type 2 diabetes develops because the body is unable to effectively use the insulin that it produces. Type 2 diabetes typically occurs in people over the age of 40 years who are overweight or obese. However, due to the increasing rate of overweight and obesity among children and young adults, this type of diabetes is increasingly being seen in younger age groups.

Gestational diabetes

Gestational diabetes is the type of diabetes that develops during pregnancy. It is caused by the hormones of pregnancy or by an insufficient amount of insulin. This type of diabetes usually goes away after the end of pregnancy, but it may not. Women who develop gestational diabetes and their children have a greater chance of developing diabetes later in their lives.


Diabetes can be diagnosed in people who have symptoms of diabetes (see chart) and a blood sugar of 200 mg/dl (milligrams per deciliter) or more. In people without any symptoms, diabetes can be diagnosed by one of the three tests:

HBA1C LESS THAN 5.7% 5.7 – 6.4 % 6.5% OR HIGHER
  1. Fasting blood glucose (sugar) – People are asked not to eat anything for at least 8 hours before the blood is drawn for this test.
  2. Glucose tolerance test – In this test, a fasting glucose is obtained (as above) after which 75 grams of glucose (provided through a special drink) is given to drink and another blood sugar is obtained two hours later.
  3. HbA1c – This is a blood test which shows the average blood glucose over the previous three months.

The table gives the normal blood glucose values and also the values by which a diagnosis of diabetes and prediabetes can be made.


As shown in the table above, people with prediabetes have blood sugars and HbA1c higher than normal, but not sufficiently high enough to make a diagnosis of diabetes. People with prediabetes are at an increased risk of developing diabetes. It is estimated that prediabetes progresses to diabetes at the rate of about five percent per year if there is no intervention. People with prediabetes are also at increased risk for developing heart disease and stroke.


  • Increased thirst
  • Increased urination
  • Feeling very hungry
  • Feeling very tired
  • Losing weight without trying
  • Sores that don’t heal or heal slowly
  • Leg cramps

Although these symptoms are common to both type 1 and type 2 diabetes, many patients with type 2 diabetes may not have any symptoms. Their diabetes may be detected by a routine blood test.


Lifestyle modification (diet and exercise) All patients with diabetes need to have a personal meal plan. Most patients with type 2 diabetes are overweight or obese and are advised to lose weight. For this reason, it is important they see a registered dietitian to develop their own personal meal plan that they can follow to lose weight. Patients with type 1 diabetes may have lost weight as a result of their disease; they also require a personal meal plan suitable for their nutritional needs. Individualized exercise is also prescribed. Unless there is a reason not to, most patients are advised to walk for at least 30 minutes five days a week. People with prediabetes can greatly reduce their risk for developing diabetes if they follow this exercise routine.


Type 1 diabetes

Patients with type 1 diabetes have an absolute lack of insulin, so they must inject insulin with a syringe, pen or an insulin pump, as they require insulin for survival. If they do not take insulin for 24 to 48 hours, they may develop diabetic coma, also called diabetic ketoacidosis [ket-to-as-i-do-sis], a life-threatening problem that occurs when the body cannot use sugar (glucose) as a fuel source because there is no insulin or not enough insulin. Those experiencing diabetic ketoacidosis may die if not promptly treated. Insulin for type 1 diabetes is prescribed in amounts needed to match the food intake and exercise level of the individual so that blood sugars remain in the “normal” range and are neither too low nor too high.

Type 2 diabetes

Several medications are now available which can be used in pill form or as an injection. Medications are selected carefully to match the needs of the individuals so that the blood sugars remain in the “normal” range and there are not too many unpleasant or dangerous, undesirable effects. Although patients with type 2 diabetes do not require insulin for survival, they may need it to control their blood sugars.

One of the common undesirable effects of insulin and several diabetes medications is that the blood sugar may drop to a level that is too low. This is called hypoglycemia [hi-po-gli-se-me-a]. People who experience hypoglycemia may complain of increased hunger, anxiety and sweating and may become unconscious if not promptly treated. Hypoglycemia can be avoided by carefully selecting medications and regulating the amount of individualized insulin that is prescribed and injected. People with diabetes are advised to keep some candy or sugar with them at all the times so that they can treat hypoglycemia should that occur.


Major damage to the health of people with diabetes is caused by its effect on blood vessels. Both the small and large-sized blood vessels are affected. Small blood vessel (microvascular) complications include diabetic eye disease (retinopathy). Diabetic retinopathy is the leading cause of blindness in adults. Diabetic kidney disease (nephropathy) is the leading cause of end-stage kidney disease, leading to dialysis and death. People who develop diabetic nerve disease (neuropathy) may complain of numbness and tingling in their hands and feet, ultimately leading to loss of sensation. For example, people may step on a nail or thumbtack, injure their skin and not even feel it. Minor injuries may get infected and this can ultimately lead to loss of feet (amputation). With large blood vessels (macrovascular complications), people with diabetes have a two-to-four times increased risk for developing heart attacks and stroke.

Much of the effort in the treatment of people with diabetes is directed towards preventing or delaying the onset of the complications of diabetes.

Treatment of complications

Much of the effort in the treatment of people with diabetes is directed towards preventing or delaying the onset of the complications of diabetes. Good control of diabetes, i.e., keeping the blood glucose as close to normal as possible, has been shown to reduce the risk of diabetic retinopathy and nephropathy. To lower the risk of stroke and heart attacks, other risk factors must also be addressed. These include smoking cessation, control of blood pressure, control of cholesterol, particularly “bad cholesterol” (LDL cholesterol) and keeping the glucose under control.

The American Association of Clinical Endocrinologists (AACE) suggests the following targets for these risk factors:

  • Blood pressure – less than 130/80
  • LDL cholesterol – less than 100 mg/dl
  • Triglycerides – less than 150 mg/dl
  • HbA1c – less than 6.5 percent in otherwise healthy people, but must be individualized. Higher values are acceptable in people with other co-existing health problems.

It is important for people with diabetes to know their numbers so they know that with the guidance of their doctors, they are doing the best that they can to reduce the damaging effects of diabetes. See an endocrinologist to get the most up-to-date information on the treatment of your diabetes and formulate a plan to manage your condition!

Dr. Ved V. Gossain is the Swartz Professor of Medicine and Chief of the Division of Endocrinology and Metabolism at Michigan State University. He received his M.D. degree from All India Institute of Medical Sciences, New Delhi India. He established the Endocrinology Fellowship training program at Michigan State University and has served as the chief of the section for the last 20 years. He is a Fellow of the Royal College of Physicians of Canada (FRCP©), American College of Endocrinology (FACE) and a Master of the American College of Physicians (MACP).