Dear Dr. Roach: Can you tell me why there is so much emphasis on small portions for diabetics or prediabetics? If you are watching carbs and are extremely underweight, is there still a reason to limit portion sizes?
Dear C.: The majority of people in North America with diabetes and prediabetes are overweight or obese, so limiting portion size makes sense for most. However, for the minority with diabetes or prediabetes with normal or below-normal weight, portion size no longer has the importance it does in overweight people.
A careful diet is important for everyone with diabetes. I would be cautious about the term “carbs,” since there are several different types of carbohydrates. Simple sugars and starches are the problem for diabetics, since they are rapidly converted to blood sugar. However, fruits, vegetables and whole grains are much more slowly turned into blood sugar, and along with high-quality protein and healthy fat, form the basis of a healthy diet for everybody — diabetics and nondiabetics alike.
Being underweight with diabetes should raise the possibility of type I diabetes, which is caused by autoimmune destruction of the cells in the pancreas that make insulin. Type I diabetics have no or almost no insulin, and absolutely need insulin by injection. Most people with type I are children or adolescents, but it can happen in adults. Type II diabetes is caused by resistance to insulin. Most type II diabetics have normal or even high levels of insulin. Insulin helps bring sugar from the blood into cells, but it also acts as a growth hormone. That’s one of the reasons type II diabetics have trouble losing weight, since the high insulin levels promote fat deposition. Type II diabetes is more common in adults, but as North Americans continue to have increasing rates of obesity, type II diabetes is showing up at younger and younger ages.
The situation is even more complex than I have made it here. There are people with elements of both type I and II diabetes, and even rarer types. I believe type I diabetics should be managed by an endocrinologist. Sophisticated blood tests, including insulin, C-peptide and insulin antibodies, occasionally are necessary to sort out what kind of diabetes is present.
Dear Dr. Roach: For several years, my husband has been drinking at least four cans, if not more, of Diet Pepsi a day. He is 68 years old. What are the long-term effects? What is this doing to his well-being now?
Dear B.A.: On the good side, four cans of Diet Pepsi have only about the same amount of caffeine as a cup of coffee, and there’s no sugar. On the downside, the sweeteners can cause some stomach trouble. The acid in the soda may hurt teeth. And, people who drink diet soda still are more likely to gain weight.
Email questions to ToYourGoodHealth@med.cornell.edu.