Double-Blind Crossover Trial of Isophane (NPH)- and Lente-Based Insulin Regimens

Abstract

Isophane (NPH) and lente insulin preparations have been the basis of insulin-injection regimens for many decades but were never formally compared. After a 2-mo run-in period, 82 patients were randomized to NPH (Protaphane) or lente (Monotard) insulin preparations given together with Actrapid as a twicedaily injection regimen in a double-blind study. Patients were seen monthly and crossed over after 5 mo of treatment. Control as assessed by glycosylated hemoglobin (NPH 9. 2 ± 0.1%, lente 9.3 ± 0.1%, mean ± SE) and fructosamine (1.55 ± 0.02 and 1.57 ± 0.02 mM) concentrations was identical for the two regimens as were home-collected laboratory-measured fasting blood glucose (BG) (NPH 8.8 ± 0.5 mM, lente 9.0 ± 0.5 mM) and mean BG (8.2 ± 0.3 and 7.6 ± 0.3 mM) concentrations. For both regimens, the major control problem was the BG concentration before and after breakfast. Total insulin dosage was similar (NPH 56.3 ± 0.6 U/day, lente 57.2 ± 0.6 U/day) with no tendency for a difference in the evening intermediateacting dose (NPH 17.0 ± 0.3 U/day, lente 17.0 ± 0.3 U/day) to counter fasting hyperglycemia. Serum lipid concentrations and body weight confirmed the equivalence of control. Hypoglycemic events were recorded in personal diaries and graded by predetermined criteria. Self-treated, relative-assisted, and hospital/doctor-treated hypoglycemic events did not differ in frequency. We conclude that lente- and NPH-based twice-daily human insulin regimens give indistinguishable metabolic control.