November is American Diabetes Month, a time to raise awareness about the prevention, treatment and consequences of this serious medical condition. More than 26 million Americans have been diagnosed with diabetes and another 79 million have prediabetes, putting them at risk for developing diabetes in the future. Fortunately, most cases of diabetes can be treated or prevented through healthy eating, weight control and regular exercise.

Diabetes mellitus is a metabolic disorder characterized by high blood glucose (sugar) caused by a lack of insulin production or impaired insulin action. Normally, when blood glucose is high – after a meal – the hormone insulin is released from the pancreas causing the body’s cells to take glucose out of the blood. If the pancreas doesn’t produce enough insulin or if the cells don’t respond to the insulin, blood glucose remains high. This is called hyperglycemia.

There are three major types of diabetes:

Type 1 diabetes is an autoimmune disorder that is usually diagnosed in childhood. Damage to the pancreas by the immune system results in a lack of insulin production, so type 1 diabetics require insulin injections.

Type 2 diabetes tends to occur in adults and is associated with obesity, particularly excess abdominal fat and physical inactivity. In type 2 diabetes the pancreas produces insulin but the cells do not respond to it, a condition called insulin resistance. The vast majority of diabetics have type 2 diabetes.

Gestational diabetes occurs during pregnancy in women who are not diabetic. Although this condition tends to resolve itself after childbirth, it may lead to a higher risk of type 2 diabetes in the future. One consequence of gestational diabetes is having a baby with a high birth weight.

Diabetes is diagnosed based on blood glucose level and symptoms including excessive thirst and hunger, frequent urination, blurred vision and weight loss. A common test is a fasting blood glucose test in which blood glucose is measured at least eight hours after a meal, usually in the morning. Another test is an oral glucose tolerance test in which blood glucose is measured for two hours after drinking a special beverage containing glucose, measuring the body’s response to glucose. The hemoglobin A1C test is a long-term measure of blood glucose control. This is important because the higher the hemoglobin A1C level, the greater the risk of diabetes complications.

In all types of diabetes, control of blood glucose through diet, exercise and medication is essential. Over time, high blood glucose levels can cause nerve and blood vessel damage leading to vision problems, lack of sensation in the hands and feet (neuropathy), kidney damage and poor wound healing. In fact, diabetes is a leading cause of blindness, foot amputation and kidney dialysis and transplants. Additionally, type 2 diabetes tends to be associated with high blood pressure, high triglycerides, low HDL (good) cholesterol and obesity. This combination is called the metabolic syndrome. The treatment of diabetes involves several approaches: regular blood glucose testing, proper use of medications, planning healthy meals and regular exercise.

Blood glucose is typically tested several times throughout the day in order to maintain normal blood glucose levels. Type 1 diabetics (and some type 2 diabetics) require injections of insulin. Type 2 diabetics may also take medications known as oral hypoglycemics which also lower blood glucose. In order to be effective and to prevent hypoglycemia (abnormally low blood glucose) medications must coordinated with meals, exercise, and other activities.

Exercise is important for blood glucose control because exercise causes an increase in the uptake of glucose into cells and can improve glucose tolerance and insulin sensitivity. In addition, exercise has the added benefits of promoting weight loss and improving strength and fitness. Diabetics should be careful to wear comfortable, supportive shoes and avoid exercise that raises blood pressure significantly. Blood glucose should be tested before exercise. If it is too low, a snack containing carbohydrates should be consumed prior to exercise. If it is too high, exercise should be postponed.

Meal planning involves selecting healthy foods to help maintain consistent blood glucose levels while meeting energy needs for exercise and other activities. The dietary recommendations for preventing and treating diabetes are almost identical to the general recommendations for good health: Emphasize whole grains, fruits, vegetables, legumes, and low-fat meat and dairy and reduce saturated fat, cholesterol, added sugars, and salt. The diet should also promote weight loss and weight maintenance, especially for overweight patients.

While many diabetics believe that carbohydrates should be avoided, this is not true. Whole grains and complex carbohydrates (whole wheat bread, for example) should make up the majority of calories. Sugars and refined grains (white bread) should be minimized. However, both sugar and alternative sweeteners are safe when consumed in moderation, as part of a healthy diet. The glycemic index (GI), a measure of how much a food raises blood glucose, can be helpful in dietary planning, but it is not the only meal planning tool that should be used. Meals should be planned around medications and exercise in order to avoid hypoglycemia.

Proper diet, blood glucose testing, medication use, and regular exercise can improve blood glucose control, reduce the risk of other health problems, and improve quality of life in diabetics. In those with prediabetes these efforts can delay the progression to diabetes and may even result in a return to normal blood glucose. In fact, diet and exercise have been shown to be more effective than medications in preventing diabetes. Plus, these lifestyle changes lead to weight loss and improved fitness, benefits that no medication can match.

And there is good news for those people who do not have diabetes or prediabetes now: Healthy eating, regular exercise, and weight control can prevent or delay the development of diabetes as well as many other chronic diseases.

Brian Parr, Ph.D., is an associate professor in the Department of Exercise and Sports Science at USC Aiken where he teaches courses in exercise physiology, nutrition and health behavior.