I read so much about type 2 (adult-onset) diabetes being associated with obesity. About 10 years ago, I was diagnosed with type 2 diabetes. However, I weigh just 98 pounds and am five feet tall with a small frame. My age is 80 and I'm still very active. Can you explain why I developed type 2 diabetes?

Answer: Clearly, obesity is a major risk factor for type 2 diabetes. Eight-five percent of those who have developed diabetes are overweight or obese. Surprisingly though, 12 to 15 percent of adults with type 2 diabetes are of normal weight - sometimes even skinny. An article in the Aug. 8 issue of the Journal of the American Medical Association described a retrospective analysis of 2,625 people identified with type 2 diabetes that found 12 percent were of normal body weight (with a body mass index of less than 25).

There are a couple of possible explanations: First of all, it is possible to be "TOFI" - Thin Outside, Fat Inside - around the abdominal organs, especially among diabetic Asians and the elderly. Metabolically, these people are similar to visibly obese people with type 2 diabetes. In fact, the aforementioned study revealed a disturbing statistic: that these "TOFI" folks have an overall death rate nearly twice as high as obese type 2 diabetics (2.8 percent versus 1.5 percent, respectively).

A second possible explanation for the incidence of type 2 diabetes in adults of normal weight may come down to a genetic predisposition for having improper insulin production and insulin resistance. Thin people with type 2 diabetes must closely watch their carbohydrates and avoid high-glycemic foods, just like their obese counterparts.

A Dec. 17 column about cold sores incorrectly said that they are the same as canker sores. It should have said that a possible treatment for cold sores (taking the amino acid lysine at the onset) also works for canker sores.