New Look at Diabetes

The more doctors learn about diabetes, the more they are inclined to revise old theories about it and the accepted methods of treatment. In recent weeks, research physicians have come closer to a complete turnabout in their thinking. They now believe that the commonest form of diabetes, far from representing a simple shortage of the hormone insulin, is a much more complex and still mystifying disorder. They have discovered a striking paradox: the great majority of adult patients have higher-than-average levels of insulin activity in their blood at the very time that they have excess blood sugar.

There are actually two basic forms of diabetes. The kind that strikes in childhood, usually before age 15 or even in the next decade, results from a failure of the pancreas* to produce enough insulin. For this juvenile or unstable form of diabetes, the only remedy seems to be the obvious one: supply the missing insulin by injection. In some cases, insulin dosage can be reduced with the aid of one of the recently developed oral drugs. Despite its relative infrequency, it is mainly the juvenile form that makes diabetes rank as the eighth leading cause of death in the U.S., and the third ranking cause of blindness.

Half Don't Know It. By far the most common form of diabetes among the estimated 4,000,000 U.S. victims (half of whom don't know they have it) is the "mature onset" type. This develops in people who are over 40, of stocky build and overweight--but always hungry. This form, if severe, was once controlled by insulin and diet, and if mild, by diet alone. Now the milder cases do better with drugs added to diet.

In recent years, doctors began to agree that this kind of adult diabetes did not result from any failure of the pancreas to produce insulin. They speculated that insulin, although produced in the right amount, was destroyed somewhere in the body, perhaps in the liver. Now they know better. Latest findings about diabetes, confirmed independently by Stanford University's Dr. Gerald Reaven and the University of Michigan's Dr. Lawrence Power, show that the level of insulin, or at least of what they cautiously call "insulin-like activity," is actually higher in the blood of obese adult diabetics than it is in people with normal metabolism.

Vicious Circle. This paradox in what Dr. Power calls "the garden variety of mildly diabetic patients" goes part way toward explaining the diabetic's constant hunger: he keeps on eating because insulin tends to stimulate the appetite. This alone would make it hard for him to keep his weight down. But in addition, insulin stimulates the deposition of fat. Physicians insist that adult diabetes can nearly always be controlled by diet alone--if only the patient will stick to the diet. But he rarely does. At Grasslands Hospital in New York's Westchester County, Dr. Charles Weller and Dr. Morton Linder found that the more overweight the diabetic gets, the more insulin there is in his blood. And the more insulin, the more he tends to eat and thus store up more fat in an ever-widening vicious circle.

Of four drugs currently available for U.S. prescription in the treatment of adult diabetes, three are sulfonylureas: tolbutamide (Upjohn's Orinase), chlorpropamide (Pfizer's Diabinese) and acetohexamide (Lilly's Dymelor). Drs. Weller and Linder emphasize that these sulfonylureas promote the release of insulin--at least in the early stages of treatment--and thus help to make fat. They recommend sulfonylureas for patients whose weight problems are not critical and for the few who are underweight. For the overweight, they prescribe phenformin (U.S. Vitamin Corp.'s DBI), which, they say, helps both to control appetite and to speed the metabolism of blood sugar.

Most diabetologists do not make this distinction. They are still unlearning what they thought they knew. As Dr. Rachmiel Levine of New York Medical College puts it: "Many times in the history of diabetes, the elusive 'cause' was almost caught in a net of data--only to escape nimbly through a convenient hole. It is still at large."

* More specifically, certain spots in the pancreas, known for their anatomist-discoverer as "the islets of Langerhans."

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