Singapore Med J 2000 Vol 41(6) : 264-267 Original Article Evaluation of N ew W HO Diagnostic Criteria for Diabetes on the Prevalence of Abnormal Glucose Tolerance in a H eterogeneous N epali Population –T he Implications of Measuring Glycated H emoglobin N Baral, B C Koner, P Karki, C Ramaprasad, M Lamsal and S Koirala Department of Biochemistry and Medicine B P Koirala Institute of Health Sciences Dharan, Nepal N Baral, MD Assistant Professor B C Koner, MD Assistant Professor P Karki, MD Associate Professor C Ramaprasad, PhD Assistant Professor M Lamsal, PhD Assistant Professor S Koirala, MD Vice Chancellor Correspondence to: Dr Nirmal Baral Email: nirmalbaral@ hotmail.com Fax: 00977-25-20251 ABSTRACT Aim of the study: T he present study was designed to (a) evaluate the implications of revised W HO diagnostic criteria on prevalence of abnormal glucose tolerance, (b) compare glycated hemoglobin level amongst healthy, impaired glucose tolerance (IGT), impaired fasting glucose (IFG) and diabetic subjects and (c) evaluate the assay of glycated hemoglobin in screening IGT, IFG from normal subjects. Methodolo g y: Hospital based, cross-sectional study. Plasma glucose and glycated hemoglobin (gHb) were estimated by glucose oxidase and affinity chromatography method respectively. Results: The crude prevalence of IFG, IGT and diabetes were 9%, 18% and 5.29% respectively with no significant difference between Mongol and non- Mongol population. N ewly introduced IFG group falsely incorporate 12% diabetic subjects and fails to detect 83% IGT subjects as impaired glucose metabolism. The gHb level is raised in IGT and diabetic group but not in IFG group. Conclusion: The assay of gHb may be used to screen abnormal glucose tolerance but paired estimation of fasting glucose increases the reliability of diagnosis. T he level of gH b in mild carbohydrate intolerance mostly depend on the level of rise in post prandial glucose (where the variation is wide, as in IGT) but not on the narrow variance in fasting plasma glucose level as found in IFG. Keywords: Glycated hemoglobin (gH b), Impaired fasting glucose (IFG), Diabetes mellitus, Impaired glucose tolerance (IGT) Singapore M ed J 2 0 0 0 Vol 4 1 (6 ):2 6 4 -2 6 7 INTRODUCTION: Diabetes mellitus affects millions of people throughout the world, which is widely prevalent chronic debilitating disease to cause short term and long term complications. Diagnosis of diabetes is done by measuring blood/ plasma glucose level. Besides diabetes mellitus, in 1985, WHO introduced impaired glucose tolerance (IGT) as a new category of abnormal response following oral glucose tolerance test (OGTT). A fasting plasma glucose level less than 140mg % and 2 hours after load plasma glucose value in between 140-199mg % were the criteria for diagnosis of IGT (1) . Recently proposed WHO criteria (1998) and American Diabetes Association criteria (1997) have redefined diabetes and IGT. The major modification is that for diagnosis of diabetes mellitus, the diagnostic threshold for fasting glucose has been lowered from 140 to 126mg %. IGT is changed to allow for new fasting level (2,3) . The recent introduction of new intermediate category, the impaired fasting glucose (IFG) is defined as fasting glucose concentration of 110 - 126mg %. The implication of these intermediary glucose tolerance on morbidity risk (coronary artery disease, atherosclerotic disease, hypertension, obesity etc.) has been claimed (1,4,5) . The glycation of hemoglobin occurs due to non- enzymatic process and is considered a good index of long term diabetes control. Because of certain pitfalls of oral glucose tolerance test (OGTT) and measure of glycated hemoglobin (gHb) being a better measure of real life week/ month long blood glucose concentration, the gHb might be a better index of long term glucose dynamics in body (6) . The screening, diagnostic and prognostic value of glycated hemoglobin has been evaluated by many investigators (7,8,9) . In view of above the present study was designed to (a) evaluate the implication of revised diagnostic criteria on prevalence of abnormal glucose tolerance, (b) compare glycated hemoglobin amongst normal, IGT, IFG and diabetic subjects and (c) evaluate the assay of glycated hemoglobin in screening subjects with IGT and IFG.