Monday, August 31, 2009

Diabetes Mellitus

By Prakash Kansal,
MBBS, FRCPE, FACP, FACC (Retired Faculty, University of Alabama at Birmingham)

This article is going to discuss Type 1 and Type 2 Diabetes Mellitus (DM) only.

It is estimated that approximately 18 million people have DM in USA.

Definition:
Diabetes Mellitus (DM) means high blood glucose (sugar). Fasting (after 8 hour without food) blood glucose (FBG) of 126 mg/dl (100ml) or over or random blood glucose of 200 or over (times 2) with symptoms (described below) is indicative of diabetes.

Cause:
Cause of diabetes is unknown. Glucose comes from food we eat. Insulin (a hormone) secreted by pancreas (an organ of our body) transports glucose into cells of our body where it is used for energy. Diabetes is due to either deficiency of insulin as in Type-1 or ineffective insulin as in Type-2.

Type-1 DM: Autoimmune system plays major role in protecting human body from infection. In Type-1 DM, autoimmune system turns against pancreatic cells and destroys them. Genetics, environmental factors and virus infection are probably involved in it.

It is common in children and young people below the age of 30 but can occur at any age. It is present in 5 to 10 percent of the population.

Type-2 DM: It is present in 90 to 95 % of the population. Type 2 diabetics are usually 45 or older and are overweight. However obese young people can also develop it. African American, Asian American, Native American and Hispanics are more prone to develop Type 2 diabetes.

People, with Body Mass Index (BMI) of 30, have 5 times greater risk of developing Type 2 diabetes. BMI is calculated as follows: Weight in KG is divided by square of height in meters or Weight in pounds multiplied by 705 and divided by square of height in inches.

Overweight: BMI of 25 to 29.9 (Asian: 23 to 24.9);
Obese: 30 to 34.9 (Asian: 25 to 29.9);
Grossly obese: 35 to 39 (Asian: over 30) and
Morbidly obese: over 40.

Calculate your BMI

Symptoms:
Type-1 diabetics develop symptoms suddenly, usually after some kind of stress such as infection, trauma, loss of close relative etc. As person lacks insulin, blood glucose rises and leaks into urine. This leads to increased urination, thirst and appetite. As glucose is lost in the urine, person loses weight and complains lack of energy and tired feeling.

In type-2 diabetes, symptoms develop slowly. Such person usually presents with symptoms due to chronic complications of diabetes such as burning and tingling in hands and feet due to neuropathy, poor vision due to retinopathy or due to urinary tract or pelvic infection such as burning and stinging of urine or vaginal discharge. However such person may complain of increased urination, thirst and loss of weight if blood glucose is very high.

Diagnosis:
The best test, at this time, is Fasting Glucose (FPG) as most of the labs are testing plasma not whole blood for glucose. Normal FPG is less than 100 mg/dl. FPG of 126 or over is indicative of diabetes. FPG of 100 to125 mg/dl means impaired fasting glucose (IFG). Such person has high risk of developing diabetes in the future. If FPG is normal, it should be repeated in three years. If impaired, it should be repeated in 1 to 2 years or earlier if one develops symptoms suggestive of diabetes.

In a person, with high risk for developing diabetes such as family history of diabetes, history of gestational diabetes (diabetes during pregnancy), obesity etc, oral glucose tolerance test (OGTT) will help to determine the diabetic state. After overnight fast for 8 hours, one drinks 75 Gm of glucose in water. Two hours after the drink, blood is tested for glucose. Blood glucose of 200 mg/dl or over, indicates diabetes. Blood glucose, between 140 & 199, mean impaired glucose tolerance (IGT). Like IFG, such person has high risk of developing diabetes in the future.

HbA1c (percentage of hemoglobin bound to glucose), at this time, is used for monitoring blood glucose during treatment but not for diagnosis of diabetes.

Treatment:
Diet and exercise are important, both for type1 and type 2 diabetics. The amount of food (number of calories) required, will depend upon the weight of the person. Type 1 diabetics are usually underweight and need 2000 to 2500 calories a day, whereas type 2 diabetics are overweight and need fewer calories (1000 to 1500). Total amount of food eaten, should be divided in 5 to 6 meals a day (breakfast, lunch, dinner and 2 to 3 snacks). Diet should be balanced containing fruits, fresh vegetables, whole grain cereals etc and less saturated fat such as butter, cream, bacon etc. An overweight person should reduce and underweight people increase the daily intake of food to maintain normal ideal body weight.
Exercise (brisk walking, cycling, swimming etc) for 30 to 45 minutes a day for 3 to 5 days a week is recommended. When older subjects, at high risk of developing diabetes, lost 5 to 7 % of body weight by life style intervention (diet and exercise), they reduced the risk of developing diabetes by 58 %.

Drugs:
In addition to diet and exercise, type-1 diabetics need insulin. Type of insulin is to be prescribed by family physician. The dose of insulin is to be adjusted according to blood glucose results. The objective is to maintain fasting and pre-prandial (before meals) blood glucose 80 to 120, 2-hour postprandial (after meals) less than 180 and at bedtime 100 to 140 mg/dl. HbA1C reflects average blood glucose for the preceding 8 to 12 weeks before the test was done, should be between 6.5 to 7 %. It should be done twice a year but more often if diabetes is under poor control.

Initial treatment for type 2 diabetics is diet and exercise. If it does not work, then oral hypoglycemic agents (OHA) should be added. Family physician is responsible for prescribing and adjusting doses of OHA. In overweight person, first drug of choice should be Metformin as it does not cause hypoglycemia (low blood glucose) and may help to lose some weight. It is important to keep in mind that even type 2 diabetics, after sometime, may require insulin as pancreatic cells fail to produce insulin.

In conclusion: Diabetes is a chronic disease and requires long term care. It leads to blindness, kidney failure, lower limb amputations and peripheral neuropathy. Diet and exercise are very important.

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