DEAR DR. ROACH: Last year, at 57, I was diagnosed with Type 1 LADA diabetes. Initially I was put on insulin to get my blood sugar within the normal range. Then I was just on metformin until the "honeymoon period" was over. My endocrinologist is great. I now am back on insulin (six units at night). I walk anywhere between 3 and 8 miles about three times a day. My blood pressure is excellent. I initially lost about 18 pounds after diagnosis, so my weight is good.

When looking at Google, it says my life expectancy has been cut by 20 years! Yikes, I JUST retired and if I go by their gauge, I'll be passing around age 68! Is this based on someone who has had diabetes for many years, since Type 1 is usually diagnosed much earlier? The doctor said even though my initial sugars were over 500 when diagnosed, I was very healthy and that's why nothing was "destroyed." My vision was off for about a month but no permanent damage was done. Any reassurance would be appreciated! -- M.W.

ANSWER: Most people are familiar with Type 1 diabetes, with a typical onset in childhood and at a normal weight. It is caused by an autoimmune destruction of the insulin-making cells in the pancreas. People also know about Type 2 diabetes, usually adult-onset and usually diagnosed in someone who's overweight; it's caused by resistance to insulin. But there are other subtypes of diabetes, including latent autoimmune diabetes in adults (LADA). In the U.S. and Canada, it accounts for a small fraction of diabetes cases, but is more common in Scandinavian countries. It has some characteristics of both Type 1 and Type 2 diabetes, but the autoimmune nature and the usual progression to insulin need makes most experts feel it is closer to Type 1 than to Type 2. A recent paper has outlined a potential new classification of diabetes types.

The change in life expectancy from diabetes relates to how long you have had diabetes and how well controlled it has been. With outstanding diabetes control (normal or near-normal blood sugar levels), the effect on overall mortality is modest, at best. In one model, the reduction in life expectancy is less than a year. However, it certainly is possible to have life expectancy drop by 20 years with very poorly controlled, longstanding diabetes. For people with diabetes, to a very large extent, their potential to live longer (and healthier) can be improved by better blood sugar control.

For new-onset autoimmune diabetes (both Type 1 and LADA), early and aggressive blood sugar control with insulin may reduce the amount of autoimmune damage and improve long-term prognosis. Studies are in progress to evaluate this.

DEAR DR. ROACH: My granddaughter, age 21, suddenly developed a nut allergy while away at college, when she had grown up eating every type of nut there is. She had such a reaction that she had to be taken to the emergency room, tested and was given an EpiPen, which she will have to carry with her everywhere. Is this a common occurrence? Is it possible that she can grow out of this in the future? -- V.P.

ANSWER: Although food allergies most often start in adulthood, they may develop at any time of life. Peanuts and tree nuts are among the most common food allergies that develop in adults.

Outgrowing a peanut allergy is uncommon, but when it does happen, it usually happens at a young age. I would not expect her to grow out of it.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.

Editor

I have been editor of the Rockdale Citizen since 1996 and editor of the Newton Citizen since it began publication in 2004. I am also currently executive editor of the Clayton News Daily, Henry Daily Herald and Jackson Progress-Argus.