Racial and Ethnic Differences in Mean Plasma Glucose, Hemoglobin A1c, and 1,5-Anhydroglucitol in Over 2000 Patients with Type 2 Diabetes

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Abstract
Content: Recent studies have reported hemoglobin A1c (A1c) differences across racial/ethnic groups. Our diverse population allows for further investigation of potential differences in measurements of glycemia. Objectives: Our objectives were to describe and explore baseline racial/ethnic differences in self-monitored plasma glucose profiles, A1c, and 1,5-anhydroglucitol (1,5-AG) in patients with type 2 diabetes enrolled in the Assessing DURAbility of Basal vs. Lispro Mix 75/25 Insulin Efficacy trial. Design, Setting, Patients: The trial enrolled 2094 patients with type 2 diabetes, ages 30–80 yr, from 11 countries. Main Outcome Measures: Estimated mean plasma glucose (MPG), A1c, and 1,5-AG were compared among racial/ethnic groups before and after adjusting for factors affecting glycemia: age, sex, duration of diabetes, body mass index, and MPG. Results: Baseline estimated MPG ± sd was 220.0 ± 82.0 mg/dl, mean A1c was 9.0 ± 1.3%, and 1,5-AG was 5.0 ± 4.1μg/ml. Estimated MPG did not differ between Caucasian and non-Caucasian groups. A1c was higher in Hispanics (9.4 ± 1.4%; P < 0.001), Asians (9.2 ± 1.4%; P < 0.01), and patients of other racial/ethnic groups (9.7 ± 1.5%; P < 0.001) compared with Caucasians (8.9 ± 1.2%). Paradoxically, 1,5-AG was higher for Asian (5.7 ± 4.6 μg/ml) and African patients (6.2 ± 5.4 μg/ml) vs. Caucasians (4.9 ± 3.9 μg/ml) (P < 0.01). After adjusting for factors affecting glycemia, A1c was higher (all P ≤ 0.002) in Hispanics, Asians, Africans, and patients of other racial/ethnic groups, and 1,5-AG was higher in Asian and African patients (P < 0.001) vs. Caucasians. Conclusions: There were differences in A1c and 1,5-AG, but not MPG, among racial/ethnic groups. Comparisons of glycemia across racial/ethnic groups using these parameters may be problematic due to inherent biological variability and methodological issues.