NPH insulin administration by means of a pen injector

In an open randomized cross-over study 50 patients with insulin-dependent diabetes were allocated to 3 months of treatment with NPH insulin either by means of a pen injector (Insuject-X) or by conventional syringes. The needle of the NPH pen injector was removed immediately after use to avoid possible leakage of solvent. Ambulatory control was assessed every 6 weeks, including blood sampling (HbA1c and insulin antibodies) and recording of hypoglycaemia. NPH insulin containers were collected for insulin potency measurement by HPLC. A seven-point blood glucose profile was performed fortnightly by means of home blood glucose monitoring. At the end of the 6 months a questionnaire was completed. No significant changes occurred in HbA1c (difference 0.1 +/- 0.7 (SD)%), blood glucose profile, or the incidence of hypoglycaemic episodes on the two regimens. The concentration of NPH insulin in the containers remained constant. All but two of the patients preferred to continue to use the pen injector. This NPH pen injector is a reliable and efficacious tool which may also prove more convenient for the patients.