Accuracy in estimating fasting blood glucose levels by patients with diabetes.

This study was designed to assess the accuracy with which diabetic patients can estimate their fasting blood sugars (FBS) and to determine whether experience with self-monitoring of blood glucose improves this ability. Twenty patients with type II diabetes who had no experience with self-monitoring of blood glucose were compared with 17 patients who had been monitoring blood sugar regularly for the previous 8 mo. All patients were asked to estimate FBS immediately before it was measured in the laboratory. Patients were very accurate in estimating their FBS; the average error in estimation was 2 mg/dl, and 65% of patients estimated FBS within 20% of actual FBS. However, there was no evidence that experience in self-monitoring of blood glucose improved the accuracy of estimation. Additional studies are needed to determine the types of cues that patients use in estimating blood sugar.