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 5.6–6.9 mmol/l or 6.1–6.9 mmol/l) and elevated HbA1c [39–46 mmol/mol (5.7–6.4%) or 42–46 mmol/mol (6.0–6.4%)].
Results During a 5‐year follow‐up, 338 incident cases of diabetes occurred. The combination of HbA1c 39–46 mmol/mol (5.7–6.4%) and fasting plasma glucose 5.6–6.9 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, 20.5–32.0% 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 42–46 mmol/mol (6.0–6.4%) and fasting plasma glucose 6.1–6.9 mmol/l had a 100% cumulative risk of developing diabetes.
Conclusions The combination of HbA1c 39–46 mmol/mol (5.7–6.4%) and fasting plasma glucose 5.6–6.9 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 42–46 mmol/mol (6.0–6.4%) and fasting plasma glucose 6.1–6.9 mmol/l would predict definite progression to diabetes.