Glycemic characteristics in continuously monitored patients with type 1 and type 2 diabetes: normative values.

OBJECTIVE The purpose of this study was to generate normative values for periods of euglycemia as well as for daily patterns of glycemic excursions in patients with type 1 and type 2 diabetes monitored continuously for a maximum period of 21 days and blinded to glucose levels. RESEARCH DESIGN AND METHODS This was a multicenter, prospective observational study in which 101 consecutive patients with type 1 (n = 60) or type 2 (n = 41) diabetes underwent blinded continuous glucose monitoring. Serial glucose measurements were divided into periods of euglycemia (70-180 mg/dl), hyperglycemia (>180 mg/dl), and hypoglycemia (<70 mg/dl). The proportions of time patients were hypoglycemic, euglycemic, and hyperglycemic and the total areas under the curves (AUCs) were determined. RESULTS During the observation period the 101 subjects contributed an average 287 +/- 132 h of continuous glucose values. Subjects remained in the euglycemic range for approximately 63% of the total day, were hypoglycemic 8%, and were hyperglycemic 29%. Hypoglycemia was more prevalent nocturnally (11 vs. 7%) and hyperglycemia diurnally (31 vs. 25%). Compared with subjects with type 2 diabetes, type 1 diabetic subjects had more frequent hypoglycemic episodes per day (2.1 vs. 1.0; P < 0.001) that were of longer duration (1.1 vs. 0.7 h; P < 0.0001), reflecting a greater number of hours per day in the hypoglycemic range (2.3 vs. 1.0 h; P < 0.0001). The mean hypoglycemic AUC values were >150% higher for type 1 compared with type 2 diabetic subjects (41 vs. 16, respectively; P < 0.0001). CONCLUSIONS These normative data will assist in study and sample size planning for future investigations of continuous glucose monitoring and allow for qualitative comparisons with trials of therapeutic interventions aimed at reducing the occurrence of glycemic excursions.