Obesity Responsible for Up to Half of New Diabetes Cases in the US

Natalie Cameron, MD

A new study aimed at quantifying the impact of obesity rates on incidence of type 2 diabetes in the US suggests obesity could be directly responsible for up to 50% of all new cases of type 2 diabetes.

An analysis of data from a pair of major studies by clinicians at Northwestern University institutions, results of the analysis suggest obesity was linked to the development of type 2 diabetes in 30-53% of cases and provide insight into how other factors, including ethnicity and gender, influence this risk.

“Our study highlights the meaningful impact that reducing obesity could have on Type 2 diabetes prevention in the United States. Decreasing obesity needs to be a priority. Public health efforts that support healthy lifestyles, such as increasing access to nutritious foods, promoting physical activity and developing community programs to prevent obesity, could substantially reduce new cases of Type 2 diabetes,” said lead investigator Natalie Cameron, MD, a resident physician of internal medicine at the McGaw Medical Center of Northwestern University, in a statement.

With obesity representing a major risk factor for diabetes and the prevalence of both increasing in the US, investigators designed the current study with the aim of quantifying the obesity-related population attributable fraction (PAF) for type 2 diabetes. For the purpose of their analyses, investigators designed their study using information from Multi-Ethnic Study of Atherosclerosis (MESA) and National Health and Nutrition Examination Survey (NHANES).

To ensure comparability in their study, investigators included women between the ages of 45-79 years old who were considered non-Hispanic White, non-Hispanic Black, or Mexican Americans from MESA and NHANES. Of note, MESA participants were required to be free of diabetes at baseline and NHANES participants were required to be free of cardiovascular disease at baseline.

Of the 4200 MESA participants included in the study, 53.9% were non-Hispanic white, 32.9% were non-Hispanic Black, and 13.3% were Mexican American. This group had a median age of 61.0 years, a median BMI of 27.9 kg/m2, and 46.8% were men. Investigators noted participants from MESA and NHANES had similar distribution by sex and BMI. Investigators also noted a greater proportion of participants with obesity had an annual income of $50,000 or less and were more likely to be non-Hispanic Black and Mexican American in both MESA and NHANES.

When examining data from MESA, investigators found the overall incidence of diabetes was 11.6% over a median follow-up of 9.2 years. The rate of diabetes was higher among patients with obesity (20%) compared to those without obesity (7.3%). In adjusted analyses, obese patients were at a 2.7-times greater risk of developing diabetes compared to those without obesity (JR, 2.7; 95% CI, 2.2-3.3).

When examining data from NHANES, results indicated the overall prevalence of obesity increased between the study’s 2001-2004 and the 2013-2016 survey cycles, with a prevalence of 34% (95% CI, 32-37) in the first cycle and 41% (95% CI, 39-44) in the last. Upon analysis, adjusted PAFS were 0.35 (0.29-0.40) in 2001-2004 and 0.41 (0.36-0.46) in 2013-2016. Investigators pointed out the greatest difference in obesity prevalence and diabetes was observed among non-Hispanic White females.

“Our study confirms there is a higher prevalence of obesity among non-Hispanic Black adults and Mexican-American adults compared to non-Hispanic white adults. We suspect these differences may point to important social determinants of health that contribute to new cases of Type 2 diabetes in addition to obesity,” added Cameron.

This study, “Quantifying the Sex-Race/Ethnicity Specific Burden of Obesity on Incident Diabetes in the US, 2001-2016: The Multi-Ethnic Study of Atherosclerosis and National Health and Nutrition Examination Survey,” was published in the Journal of the American Heart Association.