Prevalence of prediabetes in healthy adults using hemoglobin A1c versus fasting plasma glucose - The GAPP study

Abstract

Purpose: According to current guidelines, both hemoglobin A1c (HbA1c) and fasting plasma glucose (FPG) are appropriate tools to screen for prediabetes and established diabetes. However, the correlation between HbA1c and FPG in this context is not well studied, especially among young and healthy adults. Methods: The Genetic and Phenotypic Determinants of Blood Pressure and Other Cardiovascular Risk Factors (GAPP) study is a population based cohort of healthy adults aged 25-41 years in the Principality of Liechtenstein. Main exclusion criteria are a prevalent cardiovascular disease, a prior diagnosis of diabetes and a body mass index (BMI) >35 kg/m2. FPG and HbA1c were assayed using a Roche Cobas 6000 (F. Hoffmann - La Roche) and high-performance liquid chromatography (Bio-Rad D-10), respectively. Prediabetes was defined according to the current guidelines as FPG between 5.6 and 6.9 mmol/l and/or HbA1c between 5.7 and 6.4%. Results: Of 1568 subjects who completed the baseline examination, 839 (53.5%) were women, mean age was 36.4(plus or minus)4.9 years and the mean BMI was 24.7(plus or minus)3.7 kg/m2. Obesity (BMI (greater-than or equal to)30 kg/m2) was present in 156 (9.9%) participants. The correlation coefficient between HbA1c and FPG was 0.25 (p<0.0001). Overall, 476 (30.4%) had prediabetes. The prevalence was 36.6% among men and 25.2% among women (p<0.0001). A diagnosis of prediabetes was present in 427 (27.2%) by HbA1c criteria only, 98 (6.3%) by FPG criteria only and 49 (3.1%) by both criteria, as shown in Table 1. Compared with men, women were more likely to be diagnosed with prediabetes by HbA1c criteria, and less likely to be diagnosed by FPG criteria (p<0.0001, Table 1). (table Presented) Conclusion: The prevalence of prediabetes among young and healthy adults is highly dependent on the test used and is much higher using HbA1c criteria, especially among women. If confirmed, our findings may have important implications for screening recommendations in the population.