Minimal influence of the time interval between injection of regular insulin and food intake on blood glucose control of type 1 diabetic patients on abasal-bolus insulin scheme

The present study aimed at investigating the influence of the time interval between injection of regular insulin and meal ingestion on postprandial gl ucose changes and overall blood glucose control in patients with type 1 dia betes on intensive insulin therapy. Fifteen C-peptide negative subjects wer e submitted, in a randomized order, to two 6-week treatment periods in whic h regular insulin was injected either 5 minutes or 30 minutes before each o f the three main meals, in combination with a bedtime NPH insulin injection . The changes in plasma glucose excursions following a breakfast test (C-ma x, T-max, C-min, T-min, AUC(0-240 min)) were similar in the two experimenta l protocols. Furthermore, no significant changes were observed in daily ins ulin dosages nor in glucose profiles obtained using home blood glucose moni toring. Only a tendency to a greater 90-minutes postprandial increase in bl ood glucose levels was observed when regular insulin was injected 5 minutes rather than 30 minutes before meal. Glycated haemoglobin levels were simil ar after each treatment period (7.6 +/- 0.2 % versus 7.5 +/- 0.2 %; NS) and no differences in the incidence or severity of hypoglycaemic episodes were noticed between the two insulin schemes. In conclusion, in type 1 diabetic patients who are rather well controlled with a basal-bolus insulin scheme, the injection of regular insulin 30 minutes before each main meal provides no significant advantage as compared to the injection of regular insulin 5 minutes before meal.