Isolated HbA1c identifies a different subgroup of individuals with type 2 diabetes compared to fasting or post-challenge glucose in Asian Indians: The CARRS and MASALA studies.

Abstract

AIMS\nGuidelines recommend hemoglobin A1c (HbA1c) as a diagnostic test for type 2 diabetes, but its accuracy may differ in certain ethnic groups.\n\n\nMETHODS\nThe prevalence of type 2 diabetes by HbA1c, fasting glucose, and 2\u202fh glucose was compared in 3016 participants from Chennai and Delhi, India from the CARRS-2 Study to 757 Indians in the U.S. from the MASALA Study. Type 2 diabetes was defined as fasting glucose\u202f≥\u202f7.0\u202fmmol/L, 2-h glucose\u202f≥\u202f11.1\u202fmmol/L, or HbA1c\u202f≥\u202f6.5%. Isolated HbA1c diabetes was defined as HbA1c\u202f≥\u202f6.5% with fasting glucose\u202f<\u202f7.0\u202fmmol/L and 2\u202fh glucose\u202f<\u202f11.1\u202fmmol/L.\n\n\nRESULTS\nThe age, sex, and BMI adjusted prevalence of diabetes by isolated HbA1c was 2.9% (95% CI: 2.2-4.0), 3.1% (95% CI: 2.3-4.1), and 0.8% (95% CI: 0.4-1.8) in CARRS-Chennai, CARRS-Delhi, and MASALA, respectively. The proportion of diabetes diagnosed by isolated HbA1c was 19.4%, 26.8%, and 10.8% in CARRS-Chennai, CARRS-Delhi, and MASALA respectively. In CARRS-2, individuals with type 2 diabetes by isolated HbA1c milder cardio-metabolic risk than those diagnosed by fasting or 2-h measures.\n\n\nCONCLUSIONS\nIn Asian Indians, the use of HbA1c for type 2 diabetes diagnosis could result in a higher prevalence. HbA1c may identify a subset of individuals with milder glucose intolerance.