Spotlight on trends in diabetes prevalence and outcomes

Several recent analyses of national health care data assessed the prevalence of diabetes and its complications in the U.S.

In the first study, in the April 15 Annals of Internal Medicine, researchers compared National Health and Nutrition Examination Surveys from 1988-1994 and 1999-2010. They found that confirmed diabetes (either self-reported or elevated HbA1c and fasting glucose) increased from 5.5% in 1988-1994 to 7.6% in 1999-2004 to 9.3% in 2005-2010. The change is mainly explained by increases in obesity, the researchers stated. Prediabetes, defined as an HbA1c between 5.7% and 6.4%, increased from 5.8% of the population in 1988-1994 to 12.4% in 2005-2010.

In children, both type 1 and type 2 diabetes have been on the rise, according to an analysis of selected U.S. geographic areas published in the May 7 Journal of the American Medical Association. Between 2001 and 2009, prevalence of type 1 diabetes in 0- to 19-year-olds increased from 1.48 to 1.93 per 1,000, a 21.1% rise. In the same time, type 2 diabetes increased in 10- to 19-year-olds from 0.34 to 0.46 per 1,000, a 30.5% rise. The study authors noted that similar trends have been observed around the world and called for further research to investigate the causes.

On a positive note, the proportion of diabetes cases that were undiagnosed decreased from 16% in 1988-1994 to 11% in 2005-2010, the study in Annals found. Control of diabetes also improved, with the proportion of diabetes patients having an HbA1c under 7% increasing from 50.9% in 1988-1994 to 58.8% in 2005-2010. This improvement in control was not seen in minority groups, however. The increase in overall glycemic control can probably be attributed to improvements in diagnosis, screening, and care, the authors said, but the results show that many patients, especially non-Hispanic blacks and Mexican-Americans, still have high HbA1c levels. “Clinical inertia is still a problem,” noted an accompanying editorial.

Complication rates among diabetic patients have also declined in recent decades, according to another study, published in the New England Journal of Medicine on April 17. Researchers used several national surveys to compare rates of 5 common diabetes complications between 1990 and 2010. Among diabetics, acute myocardial infarction declined by 67.8% during the time period, deaths from hyperglycemia crisis declined 64.4%, stroke declined 52.7%, lower-extremity amputation declined 51.4%, and end-stage renal disease declined 28.3%. Rates of these problems declined among non-diabetic adults, too, but to a lesser degree. Because the overall prevalence of diabetes increased during the time period, only myocardial infarction and death from hyperglycemic crisis declined overall in the population (2.7 and 0.1 fewer cases per 10,000, respectively). The study authors attributed the gains to improvements in clinical care, the health care system, and health promotion efforts but noted that the total burden of complications is likely to increase if diabetes rates continue to rise.