Pharmacokinetic and glucodynamic variability: assessment of insulin glargine, NPH insulin and insulin ultralente in healthy volunteers using a euglycaemic clamp technique

Aims/hypothesis: This single-dose, double-blind, randomised, parallel-group study evaluated the reproducibility in systemic exposure and glucodynamic effect of insulin glargine, NPH insulin (NPH) and insulin ultralente (ultralente) using the manually adjusted euglycaemic clamp technique. Methods: In total, 36 healthy volunteers received two consecutive s.c. injections (0.4 IU/kg) of glargine, NPH or ultralente with a wash-out period of 7 days between treatments. Results: In healthy volunteers, glargine presented well-reproduced flat concentration profiles and no pronounced peaks in activity. NPH, by contrast, showed well-defined peaks in concentration and glucose disposal, while ultralente had highly variable profiles. Within-subject variability (ANOVA) for insulin exposure over 24 h was 15% for glargine and 19% for NPH, compared with 67% for ultralente (p < 0.05, glargine and NPH vs ultralente). The 49% within-subject variability in total glucose disposal (glucose infusion rate [GIR]-AUC(0-24 h)) with ultralente was about twice as large as the 22% with NPH (p < 0.05), but was intermediate with glargine at 31% (p=NS). By contrast, variability in the diurnal time-action profile (SD of diurnal day-to-day differences in GIR) for glargine was 30% (p < 0.05) and 50% (p < 0.05) less than with NPH and ultralente, respectively. No serious adverse events were reported. Conclusions/interpretation: Although representing insulins of different profiles, glargine and NPH showed a high and similar reproducibility of total absorption and glucodynamic effect, whereas ultralente proved to have poor reproducibility. However, while NPH yields peaks in concentration and activity, glargine shows flat and non-fluctuating profiles resulting in less variation in day-to-day 24-h activity.