A1C Cut Points to Define Various Glucose Intolerance Groups in Asian Indians

Abstract

OBJECTIVETo determine A1C cut points for glucose intolerance in Asian Indians.RESEARCH DESIGN AND METHODSA total of 2,188 participants without known diabetes were randomly selected from the Chennai Urban Rural Epidemiology Study. All had fasting plasma glucose (FPG) and 2-h postload plasma glucose measurements after a 75-g load and were classified as having impaired fasting glucose (IFG) (American Diabetes Association [ADA] criteria, FPG ≥5.5 and <7 mmol/l, and World Health Organization [WHO] criteria, FPG ≥6.1 and <7 mmol/l), impaired glucose tolerance (IGT) (2-h postload plasma glucose ≥7.8 and <11.1 mmol/l), or diabetes (FPG ≥7 mmol/l and/or 2-h postload plasma glucose ≥11.1 mmol/l). A1C was measured using the Bio-Rad Variant machine. Based on receiver operating characteristic curves, optimum sensitivity and specificity were derived for defining A1C cut points for diabetes, IGT, and IFG.RESULTSMean ± SD values of A1C among subjects with normal glucose tolerance, IGT, and diabetes were 5.5 ± 0.4, 5.9 ± 0.6, and 8.3 ± 2.0%, respectively (Ptrend < 0.001) with considerable overlap. To identify diabetes based on 2-h postload plasma glucose, the A1C cut point of 6.1% had an area under the curve (AUC) of 0.941 with 88.0% sensitivity and 87.9% specificity. When diabetes was defined as FPG ≥7.0 mmol/l, the A1C cut point was 6.4% (AUC = 0.966, sensitivity 93.3%, and specificity 92.3%). For IGT, AUC = 0.708; for IFG, AUC = 0.632 (WHO criteria) and 0.708 (ADA criteria), and the A1C cut point was 5.6%.CONCLUSIONSIn Asian Indians, A1C cut points of 6.1 and 6.4% defined diabetes by 2-h postload plasma glucose or FPG criteria, respectively. A value of 5.6% optimally identified IGT or IFG but was <70% accurate.

Evidence-based risk assessment and recommendations for physical activity clearance: diabetes mellitus and related comorbidities1This paper is one of a selection of papers published in this Special Issue, entitled Evidence-based risk assessment and recommendations for physical activity clearance, and has undergone the Journal’s usual peer review process.

“…Although not currently used as a screening tool in Canada, individuals with a HbA1c of ≤6.0% are considered normal, while values of 6.1%-6.9% could be considered as having prediabetes and those with values ≥7.0% are considered as having diabetes (Buell et al 2007). However, these cut points for diagnosis of prediabetes and diabetes may not be appropriate for certain high-risk ethnicities (Mohan et al 2010). The HbA1c measurement is the current standard for the measurement of metabolic control in persons already diagnosed with diabetes.…”

Estimation of Hemoglobin A1c Using the Complete Blood Count Measures in the Diagnosis of Diabetes

“…However, HbA 1 c is the recommended diagnostic test for the clinical assessment of diabetes using a threshold (HbA 1 c ≥6.5% [7.7 mmol/L]) recommended by the American Diabetes Association and the European Association for the study of diabetes [13,31]. Moreover, HbA 1 c is also preferred than FBG because it requires overnight fasting, and whereas HbA 1 c test can also be carried out without any restrictions.…”

“…In the case of diabetes, excess glucose in the blood attaches to Hb molecule and elevates the level of HbA 1 c [4]. The measure of HbA 1 c is clinically regarded as an index of diabetes diagnosis [13]. Elevated levels of HbA 1 c can impair endothelium-mediated vasoactive responses that can result in cardiovascular diseases among diabetic individuals [14].…”

Utility of glycosylated haemoglobin in diagnosing diabetes in an urban Sri Lankan community

“…According to studies from different countries, suggested cut-off to diagnose diabetes ranged from 5.6% to 7.0% [11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Age, ethnicity, genetic makeup and erythrocyte life-span are likely to contribute to inter-individual variability of glycosylation of haemoglobin and could be responsible for observed differences in the cut-offs in different populations [15,19,[25][26][27].…”