Shifting Definitions: The Diabetes "Epidemic"

Bodies don't change.

Human physiology is essentially the same now as it was twenty years ago; a hundred years ago; a thousand years ago. What has changed, of course, is our environment (in terms of sanitation, diet, activities, etc.) and our understanding of that physiology, which includes our ability to affect it through our technology, drugs and so on. Of course there are new microbes that have evolved in our environment (HIV, SARS, various other multiply resistant bacteria, etc.) but while they may tax our bodies' abilities to deal with them, those bodies don't really change.

Frequent mention has been made of the "epidemic" of diabetes, usually attributed to an increased incidence of obesity, which in turn is attributed to a higher consumption of processed foods and a decrease in exercise. These things may well be true, but there's something else that has changed just over the years I've been in practice that undoubtedly accounts for a certain percentage of the increased "incidence" of diabetes: the increased understanding of disordered glucose metabolism (and the associated role of dyslipidemia) and accelerated atherosclerosis.

Back when I was in medical school, the cut-off for an abnormal fasting blood sugar was 140. Today it's 100. We measured cholesterol, but there wasn't much we could do about it, so we didn't pay much attention unless it got over 300. We didn't even have glycosylated hemoglobin measurements; in fact, fingerstick machines for home use were just being developed. Over the years I have seen a "normal" fasting blood sugar (roughly defined by the "normal ranges" on the lab reports) drop; first from 140 to 125, then to 115, then 110, and now 99.

In retrospect, how many patients in years gone by were reassured by us that they didn't have diabetes, when by today's criteria they would indeed be diagnosed as such? Because I don't really believe that human metabolism has changed radically in only the twenty-some years since I've been in the medical field, I believe that a great many people considered to be in perfect health by the definitions of the times were in fact what we would now consider at fairly high risk for cardiac events. Along with the greater prevalence of smoking in decades past, I think this accounts for the phenomenon of "perfectly healthy" 50-somethings dropping dead of "coronaries" back in the 1960's and even into the 1970's. Although the criteria at the time said that they weren't diabetic, I think many of them probably were, at least by our current understanding of the disease.

What does that mean for patients today? Just as the "epidemic" of autism is recognized to be in large part a function of expanded definition (and perhaps greater recognition) of the condition, I believe that a greater number of people are being recognized as having the syndrome of insulin resistance -- which can progress to diabetes in the setting of carbohydrate overload and chronic couchpotato-hood -- thus artificially inflating the numbers of "people in this country with diabetes."

I don't mean to minimize the roles of a Mickey D on every corner and an SUV in every garage. Certainly a higher percentage of the population carrying the insulin resistance gene go on to express it in terms of glucose intolerance and frank diabetes when they pig out on carbs and never walk farther than the refrigerator than in decades of yore. But I am convinced that the expanded definition of diabetes in recent years contributes a hefty chunk to this "epidemic."