Interval between insulin injection and eating in relation to blood glucose control in adult diabetics

In a survey of 225 diabetics treated with insulin 24 (10.6%) claimed never to have received advice concerning the interval between insulin injection and eating. Of the remainder, 67 (33%) admitted disregarding advice and using shorter intervals. There was a significant (p less than 0.01) difference between the reported frequencies of clinical hypoglycaemia in patients using different intervals. The effects on glucose control of intervals between insulin injection and breakfast of zero, 15, 30, and 45 minutes were studied for periods of one week in 11 patients with type I diabetes who were receiving twice daily injections of monocomponent porcine insulins and high fibre, high carbohydrate diets, using standard home blood glucose monitoring techniques to measure blood glucose concentrations each morning. The delay of 45 minutes resulted in the lowest frequency of hypoglycaemia and the most acceptable pattern of glucose concentrations measured one and two hours after breakfast and before lunch. Combining results obtained at these three times, the mean increment in blood glucose concentration was smaller after allowing a delay of 45 minutes than after delays of zero (p less than 0.001), 15 (p less than 0.03), and 30 (NS) minutes. A delay of 30 minutes resulted in smaller mean increments in blood glucose concentration than did delays of zero (p less than 0.001) and 15 (NS) minutes. These results suggest that this aspect of diabetic management may be neglected, with important consequences for blood glucose control. An increase in delay between insulin injection and eating to 45 minutes would be a simple and safe way of improving blood glucose control in at least the 37% of the diabetic population surveyed in this study who currently allow less than 15 minutes.