Oakland, Calif. - Being overweight or obese is commonly associated with diabetes, but a new Kaiser Permanente study finds the connection differs widely by race or ethnicity. Members of racial and ethnic minority groups were much more likely to have diabetes or prediabetes at lower weights -- even at normal or below-normal body mass index (BMI), according to research published in Diabetes Care.
The large analysis included more than 4.9 million people of diverse backgrounds and geographies who were part of the nationwide Patient Outcomes Research to Advance Learning network. The PORTAL study group, supported by the Patient-Centered Outcomes Research Institute, includes data on more than 12 million patients contributed by all regions of Kaiser Permanente, along with HealthPartners in Minnesota and Denver Health.
Normal-weight Hawaiians and Pacific Islanders were 3 times more likely to have diabetes than normal-weight white people. Diabetes prevalence at normal BMI was 18% for Hawaiians/Pacific Islanders versus just 5% for whites; prevalence was also high for blacks (13.5%), Hispanics (12.9%), Asians (10.1%) and American Indians/Alaskan Natives (9.6%).
Disparities were also found in prediabetes but were not as pronounced. Results also differed by gender. Asians, Hispanics, and Hawaiians/Pacific Islanders had a higher prevalence of prediabetes at lower BMIs than other groups, particularly among women.
For primary care clinicians, the findings could signal a change in how they screen racial and ethnic minority patients for diabetes and prediabetes, said senior author Assiamira Ferrara, MD, PhD, a senior research scientist with the Kaiser Permanente Division of Research in Oakland, California. "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," Ferrara said.
This study is one of the largest that has examined the relationship between BMI and diabetes and prediabetes prevalence. The study also included large enough samples of some understudied minority groups to draw conclusions about them, the authors said. The study offers new information about diabetes prevalence across BMI categories among Asians, Hawaiians, Pacific Islanders, American Indians, and Alaskan Natives across the country.
This study took into account neighborhood-level measures of income and education, neither of which were found to fully explain the racial/ethnic differences in prevalence of diabetes beyond BMI. While access to primary care is a major factor in health care disparities, it was not seen as a contributor in this study because all of the patients had health insurance and were members of integrated health systems.
The authors speculated that there could be physiological differences among people of varying races and ethnicities relating to diabetes, citing the example of Asians having a higher share of body fat and visceral fat at the same BMI as other groups, which could lead to insulin resistance, prediabetes, and diabetes.
Lead author Yeyi Zhu, PhD, a research scientist with the Kaiser Permanente Division of Research, called for better understanding of how the physiological mechanisms of diabetes may vary. "Future research could focus on body composition, genetics, and other lifestyle factors that may contribute to disparities in chronic disease burden," Zhu said.
She also noted that the analysis identified a group of people at risk who don't get as much attention for diabetes risk: those who are underweight. The study found significant differences in diabetes prevalence among underweight men, ranging from 7.3% in whites to 16.8% in American Indians/Alaskan Natives.
The study was funded by grants from the Patient-Centered Outcomes Research Institute and the National Institutes of Health.
Authors also included Deborah Young, PhD; Margo A. Sidell, ScD, MSPH; and Corinna Koebnick, MSc, PhD, of the Kaiser Permanente Southern California Department of Research and Evaluation; David Arterburn, MD, MPH, of the Kaiser Permanente Washington Health Research Institute in Seattle; Matthew F. Daley, MD, of the Kaiser Permanente Colorado Institute for Health Research; Jay Desai, PhD, of HealthPartners Institute in Bloomington, Minnesota; Stephanie L. Fitzpatrick, PhD, of the Kaiser Permanente Northwest Center for Health Research in Portland, Oregon; Michael A. Horberg, MD, of the Kaiser Permanente Mid-Atlantic Permanente Research Institute; Emily McCormick, MPH, of the Denver Public Health Department; and Caryn Oshiro, PhD, of the Kaiser Permanente Hawaii Center for Health Research.
Diabetes is an active area of study for Kaiser Permanente Research.
About the Kaiser Permanente Division of Research
The Kaiser Permanente Division of Research conducts, publishes and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and society at large. It seeks to understand the determinants of illness and well-being, and to improve the quality and cost-effectiveness of health care. Currently, DOR's 600-plus staff is working on more than 350 epidemiological and health services research projects. For more information, visit divisionofresearch.kaiserpermanente.org or follow us @KPDOR.
About Kaiser Permanente
Kaiser Permanente is committed to helping shape the future of health care. We are recognized as one of America's leading health care providers and not-for-profit health plans. Founded in 1945, Kaiser Permanente has a mission to provide high-quality, affordable health care services and to improve the health of our members and the communities we serve. We currently serve 12.3 million members in eight states and the District of Columbia. Care for members and patients is focused on their total health and guided by their personal Permanente Medical Group physicians, specialists and team of caregivers. Our expert and caring medical teams are empowered and supported by industry-leading technology advances and tools for health promotion, disease prevention, state-of-the-art care delivery and world-class chronic disease management. Kaiser Permanente is dedicated to care innovations, clinical research, health education and the support of community health.