Humalog Mix 25 in patients with type 2 diabetes which do not achieve acceptable glycemic control with oral agents: results from a phase III, randomized, parallel study.

BACKGROUND: Humalog Mix 25 (Mix 25) is a premixed insulin mixture of 25% lispro and 75% neutral protamine lispro. Insulin lispro is an analog of human insulin. It is created when the amino acids at positions 28 and 29 of the B-chain of insulin are reversed. The natural sequence in human insulin at this position is proline at B28 and lysine at B29. The pharmacokinetic and pharmacodynamic profiles of insulin lispro indicate that it is more rapid acting, and therefore more physiological mealtime insulin than regular human insulin. OBJECTIVE: Primary objective of this study was to compare twice daily treatment with insulin lispro low mixture (Mix 25) to oral treatment with glibenclamide in patients with type 2 diabetes, with respect to the mean 2-hour postprandial blood glucose excursions after breakfast and dinner. SECONDARY OBJECTIVES: to compare the two treatments with regard to the following: hemoglobin A1c, fasting blood glucose, pre-dinner blood glucose, frequency of hypoglycemia, body weight, treatment satisfaction (by questionnaire). METHODS: The study described is a randomized, open-label, parallel group comparison of two treatment regimens in patients with type 2 diabetes. The study included two periods. The lead-in period lasted 10 +/- 7 days, all patients were taking glibenclamide. The treatment period lasted 16 weeks. Patients were randomized to receive either glibenclamide 15 mg daily or switch to Mix 25 before breakfast and dinner. Study design is illustrated in Fig. 1. Glycemic control was assessed by glycosylated hemoglobin (HbA1c) measurements, 4-point self monitoring blood glucose profiles, and patient reported hypoglycemia. One treatment satisfaction questionnaire (Appendix 1) was completed by each participant. RESULTS: 175 patients were included from the two participating countries (Romania--100 patients and Russia--75 patients). 85 were randomized to receive Mix 25 and 90 to glibenclamide arm. 172 patients were included in the efficacy analysis. Baseline patient characteristics did not show any differences between treatment groups for any of the demographic (age, gender, height, body weight, body mass index) or efficacy parameters (HbA1c or self monitored BG values). 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 glibenclamide group and 9.85 +/- 1.2% and 12.2 +/- 2.9 mmol/L, respectively, in the Mix 25 group. At the end point, all efficacy parameters were better improved in Mix 25 group (HbA1c, fasting blood glucose, 2-hour postprandial blood glucose). Mean HbA1c was significantly lower in the Mix 25 group than in the GB group (Mix 25, 8.5% +/- 1.3%; GB, 9.4 +/- 1.8%; P = 0.001). For all self-monitored blood glucose values (Fig. 2) a larger decrease from baseline was observed in the Mix 25 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). Percentage of patients experiencing at least 1 episode of hypoglycemia was--as predicted--higher in the Mix 25 group (44.7% versus 10.3%; P = 0.01). Patients expressed more satisfaction with Mix 25 than with GB, as measured by the weighted combined score on a treatment satisfaction questionnaire (2.0 +/- 1.3 vs 0.7 +/- 1.3). CONCLUSIONS: When glycemic control can no longer be achieved by oral antidiabetic agents, treatment with insulin should be considered as the next therapeutic option. Mix 25 provided good overall glycemic control, as well as patient treatment satisfaction.