Minorities More Likely Than Whites to Have Diabetes at Normal BMI

Marlene Busko

September 25, 2019

Ethnic minorities are more likely to have diabetes at a lower body mass index (BMI) than whites, and many even have the condition despite a normal BMI, according to new research.

Yeyi Zhu, PhD, at Kaiser Permanente Northern California, Oakland, and colleagues analyzed data from close to 5 million racially diverse adults including understudied minority groups who were part of three healthcare insurance plans in the United States.

"Compared with whites," they report, "all other racial/ethnic groups had a higher prevalence of diabetes at a given BMI with the difference being more pronounced at lower BMI levels (ie, underweight, normal weight, overweight)." 

"This study suggests that along with screening patients who are overweight and obese, minorities should probably be screened even if they have a normal BMI, particularly as they get older," senior author Assiamira Ferrara, MD, PhD, Kaiser Permanente Southern California, Pasadena, said in a statement issued by Kaiser.

The study was published online September 19 in Diabetes Care.

"Future research," said Zhu, "could focus on body composition, genetics, and other lifestyle factors that may contribute to disparities in chronic disease burden."

BMI Categories and Diabetes Risk for Different Races

Although the American Diabetes Association (ADA) recommends screening Asians for diabetes starting at a BMI of 23 kg/m2, the contribution of BMI to risk of diabetes in different racial groups is not well understood, and there is an absence of data on Hawaiians/Pacific Islanders and American Indians/Alaskan Natives, the researchers write. 

So they set out to examine ethnic disparities in the prevalence of diabetes and prediabetes by BMI category in the Patient Outcomes Research To Advance Learning (PORTAL) cohort of patients who had health insurance from Kaiser Permanente (in multiple regions), Health Partners (in Minnesota), or Denver Health.

Zhu and colleagues identified 4.9 million of the insured adults who were 20 years and older and received medical care at 10 sites in the United States in 2012-2013.

They did not differentiate between type 1 and type 2 diabetes but believe most patients had type 2 diabetes.

Diabetes was defined according to the 2010 American Diabetes Association (ADA) criteria, based on inpatient or outpatient diagnosis, or glucose or A1c values, or receipt of antihyperglycemic medicine.

Researchers divided patients into the following World Health Organization (WHO) recommended BMI categories:

  • Non-Asians: Underweight (< 18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25.0-29.9 kg/m2), obese class 1 (30.0-34.9 kg/m2), obese class 2 (35.0-39.9 kg/m2), obese class 3 (40.0-49.9 kg/m2), and obese class 4 (> 50.0 kg/m2).

  • Asians: Underweight (< 18.5 kg/m2), normal weight (18.5-22.9 kg/m2), overweight (23.0-27.4 kg/m2), obese class 1 (27.5-32.4 kg/m2), obese class 2 (32.5-37.4 kg/m2), obese class 3 (37.5-47.4 kg/m2), and obese class 4 (> 47.5 kg/m2).

Half of the cohort was white, and the rest were Hispanic (21.6%), Asian (12.7%), black (9.5%), Hawaiian/Pacific Islander (1.4%), American Indian/Alaskan Native (0.5%), or multiracial/unknown race (4.3%). The latter category was excluded from the analyses.

There were slightly more women (55.7%) than men.

Normal Weight Hawaiians Have Triple Diabetes Risk of Whites

Overall, the age-standardized prevalence of diabetes was 15.9%.

Hawaiians/Pacific Islanders (27.7%) had the highest prevalence of diabetes, followed by Hispanics (22.2%), blacks (21.4%), American Indians/Alaskan Natives (19.6%), and Asians (19.3%), which were all more than 1.5 times the prevalence in whites (12.2%).

The overall age-standardized prevalence of prediabetes was 33.4%.

The prevalence of diabetes increased with age up to age 70-79 years in all racial/ethnic groups.

Overall, 5% of white people with a normal weight had diabetes, but diabetes was twice as high in Asians (10.1%) and American Indians/Alaskan Natives (9.6%) of normal weight, and even higher in Hispanics (13.0%), blacks (13.5%), and Hawaiians/Pacific Islanders (18.0%) of normal weight.

Men had a higher age-standardized prevalence of diabetes (18.4%) than women (13.9%) overall and in the different BMI categories.  

Researchers also looked at the association between BMI and prediabetes across ethnic groups, but racial differences here were less pronounced.

Tailored Screening, Prevention, and Intervention

The findings suggest that "factors other than BMI may play more important roles in the risk of diabetes among racial/ethnic minorities," Zhu and colleagues summarize.

"Clinicians should be aware that the BMI cutoffs for increased risk of diabetes and prediabetes vary by race/ethnicity and that the risk is even high at relatively low BMI levels in racial/ethnic minority groups," they advise.  

"The findings," they conclude, "highlight the importance of tailored screening, prevention, and intervention strategies to mitigate the risk of diabetes and prediabetes."

The study was funded by the Patient-Centered Outcomes Research Institute. The authors have reported no relevant financial relationships.

Diabetes Care. Published online September 19, 2019. Abstract

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