Background: Humalog Mix25 (Mix25) is a premixed insulin mixture of 25% insulin lispro and 75% neutral protamine lispro.
Objective: The aim of this study was to quantitate the improvement in glycemic control achieved with Mix25 versus the maximum dose of glyburide (GB) in patients with type 2 diabetes inadequately controlled with GB.
Methods: In this randomized, parallel, open-label comparative study, patients with type 2 diabetes received either Mix25 before the morning and evening meals for 4 months or GB 15 mg daily for 4 months. Glycemic control was assessed by glycosylated hemoglobin (HbA1c) measurements, 4-point self-monitored blood glucose profiles, and patient-reported hypoglycemia. Patients also completed a treatment satisfaction questionnaire at the end of the study.
Results: All 172 patients were white; 85 were randomized to receive Mix25. The mean age was 59.5 +/- 8.2 years, and 35.5% (61/172) were men. The mean body mass index was 27.2 kg/m2. The mean duration of type 2 diabetes was 10.2 +/- 6.6 years, and the mean duration of sulfonylurea treatment was 5.8 +/- 5.9 years. The mean HbA1c and fasting blood glucose levels were 10.07% +/- 1.4% and 11.6 +/- 2.8 mmol/L, respectively, in the glyburide group and 9.85% +/- 1.2% and 12.2 +/- 2.9 mmol/L, respectively, in the Mix25 group. There were no statistically significant differences between the treatment groups at baseline for any of the demographic or efficacy variables. At end point, mean HbA1c was significantly lower in the Mix25 group than in the GB group (Mix25, 8.5% +/- 1.3%; GB, 9.4% +/- 1.8%; P = 0.001). A larger decrease from baseline in HbA1c and in all self-monitored blood glucose values was observed in the Mix25 group: -1.4% versus -0.7% for HbA1c, P = 0.004; -2.8 mmol/L versus -1.1 mmol/L for fasting blood glucose, P < 0.01; -5.1 mmol/L versus -1.7 mmol/L for the morning 2-hour postprandial blood glucose, P < 0.001; -2.2 mmol/L versus -0.8 mmol/L for the evening preprandial blood glucose, P < 0.05; and -4.4 mmol/L versus -1.5 mmol/L for the evening 2-hour postprandial blood glucose, P < 0.001. Patients expressed more satisfaction with Mix25 than with GB, as measured by the weighted combined score on a treatment satisfaction questionnaire (2.0 +/- 1.3 vs 0.7 +/- 1.3). The mean hypoglycemia rate (events per patient per 30 days) was significantly higher in the Mix25 group at end point (Mix25, 0.30 +/- 0.53; GB, 0.05 +/- 0.20; P < 0.001).
Conclusions: Compared with maximum-dose GB, twice-daily injections of Mix25 resulted in improved glycemic control and treatment satisfaction, and were associated with a predictably higher rate of hypoglycemia in this group of patients with type 2 diabetes who were inadequately controlled with maximum-dose GB. Although the inclusion of patients who were inadequately controlled with GB was intended to allow a comparison of the 2 treatments with respect to efficacy and tolerability in a real-life setting, a double-blind comparison in treatment-naive individuals may have resulted in a different outcome.