A single-center, randomized, double-blind, three-way crossover study examining postchallenge glucose responses to human insulin 70/30 and insulin lispro fixed mixtures 75/25 and 50/50 in patients with type 2 diabetes mellitus.
OBJECTIVE
The aim of this study was to test the ability of human insulin 70/30, insulin lispro mixture 75/25 (75% neutral protamine lispro [NPL], 25% insulin lispro), and insulin lispro mixture 50/50 (50% NPL, 50% insulin lispro) to control postprandial glucose (PPG) concentrations in patients with type 2 diabetes mellitus (DM).


METHODS
This single-center, randomized, double-blind, 3-way crossover study was conducted at the Diabetes and Glandular Disease Research Center, San Antonio, Texas. We measured serum glucose responses after a standardized breakfast test meal (500 kcal; 50% carbohydrate, 34% fat, 16% protein) in patients with type 2 DM receiving a single preprandial dose of human insulin 70/30, insulin lispro 75/25, or insulin lispro 50/50 by SC injection. All patients previously used insulin for at least 1 month prior to the study. The glucose responses were compared with those of healthy, untreated subjects administered the identical meal.


RESULTS
A total of 33 patients were enrolled (23 with type 2 DM and 10 healthy controls). The baseline characteristics of the patients were as follows: sex ratio (M:F), 17:6; mean (SD) age, 61.3 (10.0) years; mean (SD) body weight, 98.5 (13.2) kg; mean (SD) body mass index, 33.0 (3.8) kg/m(2); mean (SD) glycosylated hemoglobin, 8.1% (1.6%); mean (SD) fasting serum glucose (FSG), 158.7 (27.6) mg/dL; and 56.5% white, 8.7% black, and 34.8% Hispanic. The mean (SD) doses (U/d) of the fixed-mixture preparations were similar: human insulin 70/30, 44.1 (18.2); insulin lispro 75/25, 44.1 (18.2); and insulin lispro 50/50, 43.8 (17.8). FSG levels obtained before the test meal were not significantly different between treatments. Compared with those in healthy subjects, incremental glucose AUC values for the 4 hours after the meal (AUCglucose 0-4) for patients with type 2 DM were 6.4-fold higher with human insulin 70/30, 4.6-fold higher with insulin lispro 75/25, and 3.0-fold higher with insulin lispro 50/50. Each insulin regimen produced AUC(glucose) 0-4 and 2-hour PPG values significantly different from all other regimens (all, P < 0.05). Mean (SD) 2-hour PPG values (mg/dL) were lower with mixtures containing insulin lispro than with human insulin 70/30 and decreased as the proportion of insulin lispro within the fixed mixtures increased: human insulin 70/30, 212.6 (47.0); insulin lispro 75/25, 198.0 (67.5); and insulin lispro 50/50, 158.8 (52.3).


CONCLUSIONS
In this small study in patients with type 2 DM and healthy controls, preprandial administration of a fixed mixture containing rapid-acting or regular insulin and intermediate-acting components was associated with attenuation of the rise in PPG in patients with type 2 DM administered a test meal. Mixtures containing insulin lispro were associated with greater decreases in PPG concentrations compared with human insulin 70/30. Furthermore, greater amounts of rapid-acting insulin contained within the mixture were associated with better PPG control.
Schwartz
Sherwyn
S
Diabetes and Glandular Disease Research Center, San Antonio, Texas, USA.
Zagar
Anthony J
AJ
Althouse
Sandra K
SK
Pinaire
Jane A
JA
Holcombe
John H
JH
D000368:Aged; D001786:Blood Glucose / Q000032:analysis*; D018592:Cross-Over Studies; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D007328:Insulin / Q000031:analogs & derivatives / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin