DEAR DR. DONOHUE: Would you explain prediabetes and insulin resistance? My blood sugar was 104 (5.7). Can prediabetes be reversed with diet and exercise? – Anon.

ANSWER: After eight hours of not eating, normal blood sugar should be less than 100 mg/dL (5.5 mmol/L). If the value is 126 (6.99) or higher, then the person has diabetes. Numbers between 100 and 125 constitute a category called prediabetes. Prediabetes is not normal, but it’s also not diabetes. It’s a condition that puts people at a high risk of developing diabetes.

Prediabetes can be reversed with diet and exercise. For every 11 pounds of weight lost, the risk of coming down with diabetes decreases by about 60 percent. The diet that brings this kind of change is a diet where calories are restricted and one that emphasizes whole grains, vegetables, fruits, fiber and low-fat dairy products.

Insulin is a hormone made by the pancreas. It moves sugar from the blood into body cells. Insulin resistance means that a person’s cells don’t respond to insulin as they should. Blood sugar rises. As long as the pancreas can compensate by increasing its insulin production, blood sugar doesn’t rise too high. However, there comes a time when the pancreas can’t cope, and blood sugar enters the diabetes zone.

Body cells’ insensitivity to the action of insulin is called insulin resistance. It’s the basis for prediabetes and type 2 diabetes.

The diabetes booklet explains this common illness that has become an epidemic in North America. Readers can obtain a copy by writing: Dr. Donohue – No. 402, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6.75 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: I am a 77-year-old woman, overweight and a type 2 diabetic. About four months ago I joined a diet program and was put on a diabetic diet. After one week, I had a hypoglycemic episode. My husband called 911 when he couldn’t wake me. My blood sugar was 27 (1.5), and I was soaked with perspiration. An IV with sugar in it woke me up.

I did lose 20 pounds on the diet but quit after three months. I take two diabetes medicines. Until I went on the diet, my morning readings were between 70 (3.9) and 100 (5.5). My weight-loss counselor told me that my hypoglycemia had nothing to do with the diet or my diabetes.

Should I see a specialist? What kind? – C.J.

ANSWER: It’s reasonable to say that the calorie restriction of your diet combined with the same dose of diabetes medicines you took when you were not on the diet brought your blood sugar to such a low reading – hypoglycemia. The implications of that might not be too bad. Did you tell your doctor? If not, do so. The doctor might want to change your dose of medicines or eliminate one. That would be a major accomplishment. The fewer medicines we take, the better off we are. The doctor who prescribed your medicine can take care of this for you. If you need a specialist, an endocrinologist is the one to see.

People who take insulin or diabetes oral medicines have to be on guard against hypoglycemia. For instance, if a person on either plans to exercise hard, then that person has to increase what he or she eats or decrease the dose of medicine. Signs of hypoglycemia include confusion, fatigue, palpitations, tremors, sweating and hunger. Quickly taking in sugar is the treatment. Orange juice to which sugar has been added, raisins and sugar tablets are some of the things that can put an end to hypoglycemia.

DEAR DR. DONOHUE: Can you tell me about aquagenic pruritis? – N.J.

ANSWER: It’s itching that arises on contact with water of any temperature. The itching lasts from 40 minutes to two hours. Apparently, contact with water causes a release of histamine in the body.

Antihistamines taken prior to water exposure can dampen the reaction. Sodium bicarb in the bathwater prevents it for some. So can beta-blocker drugs like propranolol.

Polycythemia is one of the illnesses that can bring it on. For most, no other illness is involved.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.