Incidence of diagnosed diabetes may be stable or declining in many countries

An analysis of 21 mostly high-income countries or jurisdictions found a downward or stable trend in clinically diagnosed diabetes incidence in recent years, but the drivers of these trends remain unknown, an accompanying editorial comment said.

The incidence of diagnosed diabetes has been decreasing in many high-income countries, a recent study found.

Researchers conducted an international data analysis to assess the incidence of clinically diagnosed diabetes over time. They assembled aggregated data describing trends in diagnosed total or type 2 diabetes incidence from 24 sources in 21 mostly high-income countries or jurisdictions, including three in the United States. Data came from administrative or health insurance records, registries, and a health survey. The researchers modeled incidence rates using age and calendar time (1995 to 2018) as variables and reported each country's incidence trajectories separately. They also performed sensitivity analyses in which they stratified findings by diabetes definition and by type of data source. Results were published online on Feb. 23 by The Lancet Diabetes & Endocrinology.

The data included about 22 million diabetes diagnoses from 5 billion person-years of follow-up. Of 23 data sources with data from 2010 and onward, 19 had a downward or stable trend in diabetes incidence, with an annual estimated change in incidence ranging from −1.1% to −10.8%. Among the four data sources that showed an increasing trend from 2010 and onward—in Israel, Lithuania, Singapore, and the U.S. (Kaiser Permanente Northwest)—the annual estimated change ranged from 0.9% to 5.6%. The other two U.S. databases suggested a stable or downward diabetes incidence. Findings were robust to sensitivity analyses excluding sources in which the data quality was lower and were consistent in analyses stratified by different diabetes definitions.

Among other limitations, the data sources reported only on clinically diagnosed diabetes and are subject to influences from changes in diagnostic and coding practices, the study authors noted. They added that the definitions used to diagnose diabetes varied between and possibly within datasets. “Preventive strategies and public health education and awareness campaigns and other factors might have contributed to declining trends,” they concluded.

While these results are encouraging, they also raise several questions, an accompanying editorial comment said. “In particular, what might be driving these trends? Were these declines the result of interventions and policies designed to reduce the incidence of type 2 diabetes, or were they data artifacts?” the authors wrote.

The investigators suggested that these downward trends in diabetes incidence might reflect successes in the global fight against diabetes, but “it would be a big leap of faith to attribute changes in incidence at the population level, even if real, to diabetes prevention efforts, without more rigorous examination of causality,” the editorialists wrote. “Furthermore, the current and projected increase in overweight and obesity globally, which are major drivers of type 2 diabetes, represent a more dire prediction of future trends in metabolic disease.”