A1C and Diabetes Diagnosis Among Filipino Americans, Japanese Americans, and Native Hawaiians

OBJECTIVE: To examine the sensitivity and specificity of A1C ≥6.5% to diagnose diabetes among Filipino Americans, Japanese Americans, and Native Hawaiians. RESEARCH DESIGN AND METHODS: This was a cross-sectional study among middle-aged adults without prior diagnosis of type 2 diabetes who completed a 2-h 75-g oral glucose tolerance test (OGTT) and A1C measures. RESULTS: The 933 participants had a mean age of 54.2 years, and 73% were women. A total of 425 (45.5%) subjects had impaired fasting glucose or impaired glucose tolerance, 145 (15.5%) had type 2 diabetes (by OGTT), and 83 (8.9%) had A1C ≥6.5%. The sensitivity and specificity of A1C ≥6.5% to define diabetes (by OGTT) was 40.0 and 96.8% and 68.9 and 95.3%, respectively (by fasting plasma glucose only). However, (64.8%) of Filipino and Japanese subjects with diabetes had isolated postchallenge hyperglycemia; AIC ≥6.5% sensitivity and specificity was 19.1 and 92.1%, respectively, to define isolated postchallenge hyperglycemia in the total sample. CONCLUSIONS: A1C ≥6.5% had low sensitivity and may delay diagnosis of type 2 diabetes without OGTT. This limitation is exacerbated by isolated postchallenge hyperglycemia in Asian Americans.