Lispro Mix25 insulin as premeal therapy in type 2 diabetic patients

Abstract

Objective: Insulin Mix25 is a new premixed insulin analog containing 25% insulin lispro and 75% neutral protamine lispro (NPL) suspension (NPL insulin). The aim of the study was to compare serum glucose and insulin responses after breakfast in type 2 diabetic patients who received Mix25, premixed regular/NPH (30%/70%), or NPH insulin before the meal.

Research design and methods: We studied 22 type 2 diabetic patients of age 62 +/- 1 years, BMI 30 +/- 1 kg/m2, duration of diabetes 15 +/- 2 years, duration of insulin therapy 6 +/- 1 years, insulin dose 65 +/- 6 U/day, and HbA1c 7.9 +/- 0.2%. Ten healthy individuals (age 56 +/- 1 years, BMI 28 +/- 1 kg/m2) served as control subjects. Each patient (except healthy subjects, who were studied once each) was studied three times in a double-blind, randomized fashion. After an overnight fast, the patients received 36 +/- 4 U of test insulin. Ten minutes after insulin injection, the patients ingested a breakfast meal (512 kcal, 60% carbohydrate, 20% fat, and 20% protein), identical in all studies. Blood samples were taken before and at 10- to 30-min intervals for 240 min after the breakfast meal.

Results: The peak rise in serum glucose was lower after Mix25 (76 +/- 7 mg/dl) than after 30/70 (94 +/- 5 mg/dl, P < 0.05) or NPH (113 +/- 4 mg/dl, P < 0.005) insulin. The incremental area under the serum glucose curve was 36% smaller after Mix25 than after 30/70 (P < 0.01) and 56% smaller than after NPH (P < 0.005) insulin. The peak rise in serum insulin concentration was higher after Mix25 (103 +/- 18 mU/l) than after 30/70 (87 +/- 13 mU/l, P < 0.05) or NPH (62 +/- 12 mU/l, P < 0.01) insulin. The incremental area under the serum insulin curve was higher after Mix25 than after 30/70 during the first 2-3 h (P < 0.02), but the difference disappeared by the end of the 4-h follow-up period. After Mix25 injection, there was an inverse correlation between the glucose response to a meal and insulin dose (r = -0.56, P < 0.01) or the incremental area under the serum insulin curve (r = -0.39, P < 0.05). No such correlations were observed with the other insulins.

Conclusions: Because of its faster initial absorption rate, the new premixed insulin analog Mix25 reduces blood glucose response to a breakfast meal in type 2 diabetic patients compared with premixed 30/70 (regular/NPH) or NPH insulin.