Diabetes incidence is either stabilizing or declining in high-income countries, but further research is required to fully elucidate the reasons for these declines, according to research published in Lancet Diabetes Endocrinology.1

Diabetes incidence is a significantly better metric to understand trends in population risks for diabetes. In this study, researchers conducted a multicountry data analysis using aggregated data from 24 population-based data sources in 21 countries. The goal of this analysis was to determine whether the incidence of clinically diagnosed diabetes has changed over time.

Data sources included registries (25%), administrative data (50%), health insurance data (21%), and health surveys (4%) that had individual-level information on diagnosed incidence of diabetes. The primary outcome was incidence rate of clinically diagnosed diabetes; these diagnoses were attained via differing metrics across sources, including blood glucose concentration, hemoglobin (Hb)A1c, clinical diagnoses by healthcare professionals, the use of ICD-9 or ICD-10 codes, self-report, or algorithms.


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The population cohort included 22 million cases of newly diagnosed diabetes representing 5 billion person-years. In total, 4 data sources were from Asia, 19 high- and 2 middle-income sources were from Russia and Ukraine, and 3 sources were nationally representative samples.

Of these, 23 sources included data from 2010 and beyond, at which point, multiple populations demonstrated a trajectory change. Researchers compared incidence trends for each population both before and after 2010, using join points in 2009, 2010, 2011, and 2012.

At each cutoff point, 79% (19/24 populations), 83% (19/23 populations), 82% (18/22 populations), and 81% (17/21 populations) demonstrated a “significant downward trend in incidence” in 2009, 2010, 2011, and 2012, respectively. Of the 23 sources that had data from 2010 onward, 19 indicated a downward or stable trend; annual estimated change in incidence ranged from -1.1% to -10.8%. Of the 4 sources indicating an increasing trend, annual estimated change ranged from 0.9% to 5.6%.

Researchers also evaluated the data based on when HbA1c was formally introduced in each country or jurisdiction as a method of diabetes diagnosis. The United States introduced this metric in 2010; France, Latvia, Lithuania, and Ukraine have not yet had a formal recommendation to use HbA1c. Among those countries, France and Latvia have demonstrated declines in diabetes incidence.

In a related commentary, authors noted that although these data encompass a “immense volume of data,” numerous questions remained.2

“Macroepidemiological findings such as these depend on the validity of micro-level data collection and documentation,” they wrote. “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 […] Questions regarding trends in key sociodemographic groups and in low-income and middle-income countries are crucial and merit imminent attention and study.”

Limitations of the original study include the use of data sources reporting only on clinically diagnosed diabetes, which may be subject to influences from diagnostic changes and coding practices, a lack of representation of patients from low- and middle-income countries, and variations in the definition of diabetes between and potentially within datasets.

“Our analysis shows that in most of the (mainly high-income) countries for which data are available, the incidence of diabetes has been stable or falling in recent years,” according to researchers.

“Although there was a measurable shift to diabetes screening with HbA1c, this change is unlikely to be solely responsible for the declining diagnosed diabetes incidence trends,” the researchers concluded, adding that other preventative strategies, such as public health education and awareness campaigns, could also have contributed to declining trends.

Disclosure: One author of the commentary declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

References

1. Magliano DJ, Chen L, Islam RM, et al. Trends in the incidence of diagnosed diabetes: a multicountry analysis of aggregate data from 22 million diagnoses in high-income and middle-income settings. Lancet Diabetes Endocrinol. Published online February 23, 2021. doi:10.1016/S2213-8587(20)30402-2

2. Ali MK, Seiglie JA, Narayan KMV. Progress in diabetes prevention or epidemiology—or both, or neither? Published online February 23, 2021. Lancet Diabetes Endocrinol. doi:10.1016/S2213-8587(20)30433-2