Screening for pre-diabetes to predict future diabetes using various cut-off points for HbA1c and impaired fasting glucose: the Toranomon Hospital Health Management Center Study 4 (TOPICS 4)

Diabet. Med. 29, e279-e285 (2012) Abstract Aim To evaluate various screening criteria for pre-diabetes to identify which combination of impaired fasting glucose and elevated HbA1c values performs most effectively in predicting future diabetes in a large cohort of Japanese individuals. Methods The study included 4670 men and 1571 women without diabetes (diabetes: fasting plasma glucose = 7.0 mmol/l, HbA1c= 48 mmol/mol (= 6.5%), or self-reported clinician-diagnosed diabetes). Pre-diabetes was diagnosed by a combination of impaired fasting glucose (fasting plasma glucose 5.66.9 mmol/l or 6.16.9 mmol/l) and elevated HbA1c [3946 mmol/mol (5.76.4%) or 4246 mmol/mol (6.06.4%)]. Results During a 5-year follow-up, 338 incident cases of diabetes occurred. The combination of HbA1c 3946 mmol/mol (5.76.4%) and fasting plasma glucose 5.66.9 mmol/l yielded the highest sensitivity (86%) and generated a large population-attributable per cent risk (78%) for predicting development of diabetes. Among individuals classified as having pre-diabetes by any of the four combined criteria, 20.532.0% reverted to the normoglycaemic state as having neither elevated HbA1c nor impaired fasting glucose at the last follow-up examination. At 5.6 years after the baseline examination, however, pre-diabetic individuals who fulfilled both HbA1c 4246 mmol/mol (6.06.4%) and fasting plasma glucose 6.16.9 mmol/l had a 100% cumulative risk of developing diabetes. Conclusions The combination of HbA1c 3946 mmol/mol (5.76.4%) and fasting plasma glucose 5.66.9 mmol/l would have the best performance in reducing the likelihood of missing future cases of diabetes. Identifying pre-diabetic individuals who strictly fulfil HbA1c 4246 mmol/mol (6.06.4%) and fasting plasma glucose 6.16.9 mmol/l would predict definite progression to diabetes.