Fasting glucose level is associated with nocturnal hypoglycemia in elderly male patients with type 2 diabetes.

Background: Nocturnal hypoglycemia was a common and serious problem among patients with type 2 diabetes (T2DM), especially in the elderly. This study investigated whether fasting glucose was an indicator of nocturnal hypoglycemia in elderly male patients with T2DM. Methods: A total of 291 elderly male type 2 diabetic patients who received continuous glucose monitoring (CGM) between January 2007 and January 2011 were enrolled in the study. The association of fasting glucose and nocturnal hypoglycemia based on CGM data was analyzed, comparing with bedtime glucose. Results: Based on CGM data, patients with nocturnal hypoglycemia had significantly lower fasting glucose (5.88 +/- 1.29 versus 6.92 +/- 1.32 mmol/L) and bedtime glucose (7.33 +/- 1.70 versus 8.01 +/- 1.95 mmol/L) than patients without nocturnal hypoglycemia (both p < 0.01). Compared with the highest quartile, the lowest quartile of fasting glucose had a significantly increased risk of nocturnal hypoglycemia after the multiple adjustments (p(for) (trend) < 0.001). However, this association did not appear in bedtime glucose. When the prediction of nocturnal hypoglycemia either by fasting glucose or bedtime glucose using the area under receiver operating characteristic (ROC) curve, fasting glucose but not bedtime glucose, was an indicator of nocturnal hypoglycemia, with an area under the ROC curve (AUC) of 0.714 (95% CI: 0.653 +/- 0.774, p < 0.001). On the ROC curve, the Youden index was maximal when fasting glucose was 6.1 mmol/L. Conclusions: Fasting glucose may be a convenient and clinically useful indicator of nocturnal hypoglycemia in elderly male patients with T2DM. Risk of nocturnal hypoglycemia significantly increased when fasting glucose was less than 6.1 mmol/L.