Spotlight on diabetes incidence and complications

Mortality and cardiovascular complications from diabetes have gone down, but incidence rates among youth are up, according to recent studies of Swedish and American patients, respectively.

Both studies appeared in the April 13 New England Journal of Medicine. The first was an analysis of patients included in the Swedish National Diabetes Register between 1998 and 2012, followed through 2014. They were matched to controls by age, sex, and county. Among patients with type 1 diabetes, all the studied outcomes declined between the start of the study period and the end, as measured by incidence per 10,000 patient-years: death from any cause, −31.4; death from cardiovascular disease, −26.0; death from coronary heart disease, −21.7; and hospitalization for cardiovascular disease, −45.7. Patients with type 2 also saw declines on these outcomes: of −69.6, −110.0, −91.9, and −203.6 per 10,000 patient-years, respectively. Patients with type 1 diabetes had about a 40% greater reduction in cardiovascular outcomes than controls, while patients with type 2 had about a 20% greater reduction than controls. On fatal outcomes, patients with type 1 had similar declines to controls, while those with type 2 had smaller reductions than controls.

Despite these marked reductions, the results show that a substantial excess risk for all of these complications remains for patients with diabetes compared to controls, the study authors noted. The observed improvements could be attributed to a number of advances, including integrated care, patient education, clinical decision support, risk-factor management including increased use of statin and antihypertensive medications, and new revascularization and glucose-monitoring technologies, they said.

The second study ascertained incidence of type 1 diabetes among 0- to 19-year-olds and type 2 diabetes among those 10 to 19 years of age, by comparing diabetes cases at five U.S. study centers to census and health plan member counts. Overall, after adjustment for age, sex, and race or ethnic group, the study found that type 1 diabetes incidence increased by 1.8% per year from 2002-2003 to 2011-2012, and type 2 diabetes increased by 4.8% annually in the same period. The rate of increase in type 1 was significantly greater among Hispanic patients than non-Hispanic whites. For type 2, non-Hispanic whites showed a smaller increase than any of the other race or ethnic groups, with Native Americans having the greatest annual rate of increase.

The results show “a growing disease burden that will not be shared equally,” the study authors noted. The differences among ethnic groups may be due to genetic, environmental, and behavioral factors, and highlight the need to identify ways to reduce disparities, they said. An accompanying editorial said that the differing rates were “somewhat unexpected” and not likely to be explained by the obesity epidemic. Despite the improvements found in the first study, the second confirms that “the overall adverse effect of diabetes on public health is actually increasing,” the editorial said.