Background: The incidence of self-reported diagnosed diabetes may be increasing because of recent changes in the diagnostic criteria for diabetes, enhanced case detection, and a true increase in disease incidence. These factors may also be changing the characteristics of newly diagnosed cases. Therefore, we examined recent trends in the incidence of diagnosed diabetes, changes to the characteristics of incident cases, and factors associated with incidence.
Methods: First, National Health Interview Survey data for 1997 to 2003 were used to examine 7-year trends in the incidence of diagnosed diabetes among U.S. adults aged 18 to 79 years. Second, among 1997-1998 and 2002-2003 incident cases, differences in sociodemographic characteristics, risk factors, and indicators of health status were examined. Lastly, multivariate-adjusted incidence from multiple logistic regression of 2001-2003 survey data were derived.
Results: From 1997 to 2003, the incidence of diagnosed diabetes increased 41% from 4.9 to 6.9 per 1,000 population (p <0.01). Incidence increased among men and women, non-Hispanic whites, persons with at least a high school education, nonsmokers, active and inactive persons, and among obese persons (p <0.05). Obesity was more prevalent (p <0.01) and physical limitation was less prevalent (p =0.03) in 2002-2003 versus 1997-1998 incident cases. Multivariate-adjusted incidence increased with age and BMI category, and decreased with education level (p <0.05).
Conclusions: Obesity was a major factor in the recent increase of newly diagnosed diabetes. Lifestyle interventions that reduce or prevent the prevalence of obesity among persons at risk for diabetes are needed to halt the increasing incidence of diabetes.