The authors, from the CDC, say that while the decline in diabetes incidence occurred alongside public health efforts, it's too soon to assume a causal relationship.
After nearly 20 years, a fresh look at data collected by the CDC has brought some good news in diabetes: new cases are declining, and existing cases have hit a plateau.
The analysis, by authors from the Division of Diabetes Translation at the CDC, comes after more than a decade of work by public health officials to reverse America’s 20-year increase of both diabetes incidence and prevalence, which seemed to affect every demographic but was clearly worse among the poor, minority groups, and those with less education.
Published last week in the BMJ Open Diabetes Research & Care, the report examined annual results from the National Health Interview Survey from 1980 to 2017 and were calculated using annual percentage change (APC). Results were corroborated against county- and state-level estimates from the Behavioral Risk Factor Surveillance System. They show the following:
The authors also note that, while the decline in new cases came at the same time as efforts to reduce T2D, such as the National Diabetes Prevention Program and reduced intake of added sugar and sweetened beverages, “their association with diabetes incidence trends is only ecological and no causal inference can be made at present.”
While the number of Americans with diagnosed diabetes may be declining, the estimated number of Americans with prediabetes—now 84 million—remains unchanged, and the cost of the disease in 2017 was $327 billion, up from $245 billion in 2012.
Perhaps, the authors say, efforts at screening and early detection are working to prevent full-blown disease; once diagnosed, people with diabetes appear to be living longer. Authors note the plateau in diabetes prevalence is consistent with the large reductions in cardiovascular and all-cause mortality reported among adults with diabetes.
“Saturation of diagnosed diabetes is also an important consideration,” the authors write. “An increased emphasis on screening may have decreased the susceptible population, driving down incidence,” although as late as 2015, an estimated 24% of people with diabetes remained undiagnosed.
Increased access to care may affect incidence, although the article does not address this. A key study by Quest Diagnostics published in 2015 showed that the arrival of Medicaid expansion in several states captured a number of previously undiagnosed cases. That study found that among the Medicaid population in expansion states, there was a 23% increase during the first 6 months of 2014, after expansion took effect, while the increase in diagnoses in non-expansion states was 0.4%.
While the authors do not address the role of healthcare transformation, the data show that when broken down by age, the rate of decline in diabetes incidence after 2011 was greatest among those 65 to 79 years of age, (APC —8.1%, P = .09). Although this decline was not statistically significant, most of it occurred after the Medicare Shared Savings Program offered incentives to health systems to offer high-quality care to Medicare beneficiaries, with diabetes-related measures a key part of the reporting criteria.
There’s still plenty of work to do, the authors say. They note that obesity, which triggers type 2 diabetes (T2D), remains high; other CDC data show obesity is highest in states where the diabetes rates are also high.
“We caution that trends are likely affected by changing awareness, detection, and diagnostic practices,” the authors write. “Even in the event of true reductions in incidence, the high prevalence and declining mortality signifies a continuing overall burden of diabetes. For these reasons, we urge a continued emphasis on multilevel, multidisciplinary prevention to reduce both type 2 diabetes and diabetes complications.”
Benoit SR, Hora I, Albright AL, Gregg EW. New directions in incidence and prevalence of diagnosed diabetes in the USA. BMJ Open Diab Res Care. 2019;e000657. doi:10.1136/bmjdrc-2019-000657.