Cold facts on diabetes.

Cold facts on diabetes

Children's chances of developing diabetes vary dramatically, depending in part on where in the world they live, according to the first international collaborative effort to examine the incidence of insulin-dependent diabetes mellitus (IDDM) in children. The study documents wide variation in its occurrence, with the average annual incidence for children under age 15 ranging from 1.7 per 100,000 per year in Japan to 29.5 per 100,000 in Finland.

The project, begun in 1986, is based on 24 registers in 15 countries. U.S. incidence ranges from a low of 9.4 per 100,000 in San Diego to 20.8 per 100,000 in Rochester, Minn. These differences in incidence are greater than those of most chronic diseases, notes the Diabetes Epidemiology Research International Group, reporting in the August DIABETES.

The work corroborates a previously observed connection between climate and IDDM risk, with higher risk in colder regions. Examining race and ethnicity as factors, the group found lower risk among U.S. blacks and Hispanics than among U.S. whites. In New Zealand, children of European descent are at three times the risk of the Maoris and Polynesians.

Causes of these "extraordinary" distribution differences remain unknown, says Marian Rewers of the University of Pittsburgh, who took part in the study. Both genetic and environmental factors appear necessary for the disease. Thus, the study group cautions that in future studies researchers must take care in interpreting geographic and climate factors in relation to such factors as lifestyle, diet, ethnicity and the prevalence of certain viruses.

Another study published this month echoes the theme that in diabetes, things are not always what they seem. In treating IDDM, many physicians attempt to keep blood sugar levels as close to normal as possible with intensive insulin therapy. This "tight control" approach, many believe, delays or prevents diabetes' serious complications, such as kidney failure, heart disease and blindness. But first-year results from a 10-year investigation of the benefits or drawbacks of the approach show it may lead to weight gain, which itself has potentially adverse consequences.

The report of the Diabetes Control and Complications Trial, which confirms and extends the findings of smaller, uncontrolled studies, appears in the July/August DIABETES CARE. The study involves 278 diabetics who are receiving a standard or experimental treatment. Both groups follow careful diets and self-monitor their glucose levels. Patients in the standard group give themselves the one or two daily insulin injections typically used to treat IDDM. Experimental patients give themselves more than three injections a day, ore receive continuous insulin from an infusion pump, and adjust their diet and insulin to maintain strict glucose control.

Those in the intensive group gained "significantly more" weight in the first year: 5.1 kilograms versus 2.4 kg in the standard group. The researchers detected no relation between these weight changes and reported caloric intake or exercise. This leads them to suggest that improved utilization of calories produced the weight gain. "It was predictable, but this is the most scientifically valid demonstration yet that insulin causes people to gain weight," says Simeon I. Taylor of the National Institute of diabetes and Digestive and Kidney Diseases, in Bethesda, Md. "It's an exquisitely well-controlled study."

Although the significance of the weight gain remains unclear, the researchers cite two negative implications. Patients' concerns about unwanted weight gain could diminish compliance with treatment, they note, and if weight gain persists, it could lead to higher blood pressure and increased risk of cardiovascular disease.