Discordance between HbA1C and Glucose Tests for the Diagnosis of Prediabetes in a Filipino-American Cohort

BackgroundThe diagnostic accuracy of HbA1C for prediabetes has been questioned due to its discordance with fasting plasma glucose (FPG) and 2 h oral glucose tolerance test (OGTT) glucose in non-white populations. This study aims to estimate concordance in the diagnosis of prediabetes using HbA1C FPG, and OGTT in a Filipino-American cohort. MethodsCross-sectional data from 149 Filipino-Americans without known diabetes living in the San Francisco Bay Area were used to compare prevalence of prediabetes as diagnosed by HbA1C, versus diagnosis by FPG and OGTT. ResultsThirty nine percent of subjects met the diagnosis of prediabetes using any one of the measures. Overall agreement between HbA1C, FPG and OGTT was low. Prevalence was 8.1% by FPG, 8.7% by OGTT and 35% by HbA1C. BMI, waist-hip ratio, insulin, HOMA-IR, blood pressure, and triglycerides were significantly higher in those with prediabetes by HbA1C versus normal HbA1C. ConclusionsThere is significant discordance between HbA1C, FPG, and OGTT in diagnosing prediabetes in a Filipino-American cohort. HbA1C detected four times as many individuals with prediabetes than FPG or OGTT. Individuals classified with prediabetes by HbA1C had indicators of more insulin resistance compared to individuals with normal HbA1C suggesting that HbA1C appears to detect true metabolic abnormalities on the path to diabetes as opposed to detecting false positives. These results have important implications for diabetes and prediabetes screening in Filipinos.