Prevalence of diabetes and pre-diabetes in rural Tehri Garhwal, India: influence of diagnostic method

BACKGROUND: There are few available data regarding the prevalence of diabetes in the sub-Himalayan region of India. The aim of this study was to determine the prevalence of pre-diabetes and diabetes in rural Garhwal based on glycosylated hemoglobin. METHODS: In a cross-sectional survey of 500 adults from five randomly selected villages in Chamba, a mountainous Tehri Garhwal district in Uttarakhand in north-west India, we determined the prevalence of diabetes (hemoglobin (Hb) A1c ≥ 6.5%) and pre-diabetes (5.7% ≤ HbA1c ≤ 6.4%). In a sub-sample of those diagnosed with diabetes or pre-diabetes (n = 140), fasting blood glucose (FBG, n = 117) or postprandial blood glucose (PBG, n = 23), and blood hemoglobin concentration, was measured at follow-up. RESULTS: Based on HbA1c, 10.0% had diabetes and 56.4% pre-diabetes. Of those diagnosed as diabetic by HbA1c, 10 of 16 (62.5%) were diagnosed as diabetic by FBG (> 125 mg/dL) or PBG (≥200 mg/dL). In those diagnosed as pre-diabetic by HbA1c, only 55 of 124 (44.4%) were diagnosed as pre-diabetic by FBG (100-125 mg/dL) or PBG (140-199 mg/dL). A large proportion of these 140 individuals (67.1%) were moderately to severely anemic (Hb < 11.4 mg/dL). The diagnostic gap for pre-diabetes between HbA1c and FBG/PBG was similar for the groups with and without moderate to severe anemia. CONCLUSIONS: HbA1c and FBG/PBG have similar diagnostic performance for diabetes in this population. However, many individuals were diagnosed with pre-diabetes by HbA1c but not FBG/PBG. The relative excess diagnosis of pre-diabetes with HbA1c does not appear to be explained by anemia, an endemic condition in India. The prognostic significance of diagnosis of pre-diabetes by HbA1c but not FBG/PBG remains unknown, but merits investigation