Intramuscular injection of insulin lispro or soluble human insulin: pharmacokinetics and glucodynamics in Type 2 diabetes

Aim The aim of the study was to compare the pharmacokinetics and glucodynamics of insulin lispro and soluble human insulin following intramuscular (i.m.) injection in patients with Type 2 diabetes with secondary failure of sulphonylureas. Methods Single 15-U i.m. doses of insulin lispro or soluble human insulin were administered to 16 patients in a two-way, randomized, crossover design. Glucodynamic and pharmacokinetic parameters were determined over 6 h after insulin injection using clamp techniques. Results Insulin C-max was significantly higher (971 +/- 217 vs. 659 +/- 141 pmol/l, P<0.001) and T-max was significantly shorter (46.9<plus/minus>27 vs. 94.7 +/- 50.1 min, P=0.002) with insulin lispro. Glucose infusion rate (GIR) curves showed clear separation 20 min after injection and were significantly greater for insulin lispro during the 40-60, 60-80 and 80-100-minute time intervals. Total glucose infused was only approximately 5% larger with insulin lispro during the 6-h follow-up, due to lower insulinaemia at later time points. The glucose R-max and TRmax were not statistically different between insulin treatments. Conclusion This study shows that i.m. injection of insulin lispro is followed by its more rapid absorption, which results in stronger metabolic effect in the first 2 h when compared with soluble human insulin under the same test conditions.