Diabet. Med. 29, e279-e285 (2012)
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.