Racial and Ethnic Differences in Cardio-Metabolic Risk in Individuals with Undiagnosed Diabetes: National Health and Nutrition Examination Survey 1999–2008

Abstract

Although early recognition and treatment of diabetes may be essential to prevent complications, roughly one-fifth of diabetes remains undiagnosed. Examine cardio-metabolic risk factors and their control in non-Hispanic white (NHW), non-Hispanic black (NHB) and Mexican American (MA) individuals with undiagnosed diabetes. Nationally representative cross-sectional study of participants in the National Health and Nutrition Examination Survey (NHANES) continuous cycles conducted 1999 through 2008. Of 22,621 non-pregnant individuals aged ≥20years, 2521 had diagnosed diabetes. Of the remaining 20,100 individuals, 17,963 had HbA1c measured, 551 of whom were classified as having undiagnosed diabetes and comprise the study population. Undiagnosed diabetes was defined as HbA1c ≥ 6.5% without a self-report of physician diagnosed diabetes. Cardio-metabolic risk factor control was examined using regression methods for complex survey data. Among individuals with undiagnosed diabetes, mean HbA1c level was 7.7% (95% CI: 7.5, 7.9), 19.3% (95% CI: 14.2, 24.3) smoked, 59.7% (95% CI: 54.5, 64.8%) had hypertension and 96.5% (95% CI: 94.6, 98.4%) had dyslipidemia. Lipid profiles were remarkably different across racial-ethnic groups: NHB had the highest LDL- and HDL-cholesterol, but the lowest triglycerides, while MA had the highest triglycerides and the lowest LDL-cholesterol. After adjusting for age, sex, NHANES examination cycle and use of either blood pressure or lipid medication, the odds of having blood pressure ≥130/80mmHg was higher in NHB [1.92 (95% CI: 1.09, 3.55)] than NHW, while the odds of having LDL-cholesterol >100mg/dl was higher in NHW[2.93 (95% CI: 1.37, 6.24)] and NHB[3.34 (95% CI: 1.08, 10.3)] than MA. In a nationally representative sample of individuals with undiagnosed diabetes, cardio-metabolic risk factor levels were high across all racial/ethnic groups, but NHB and MA had poorer control compared to NHW. Interventions that target identification of diabetes and treatment of cardio-metabolic risk factors are needed.