We studied the effect of Timing a fixed dose of rapid acting insulin lispro (Humalog™) in twelve type 1 diabetic subjects who were all made hyperglycemic prior to a standardized diabetic meal (11). In all studies, the dose of insulin of 0.15U/kg (~10 units) remained constant and represented a typical dose utilized by type 1 diabetic patients prior to an evening meal. Each of the twelve diabetic volunteers participated in all four study arms (48 total studies). The insulin lispro was given at the following times: 1) 30 minutes prior to meal time (-30 minutes), 2) 15 minutes prior to the meal time (-15 minutes), 3) at the meal (0 minutes), and 4) 15 minutes after the meal was begun (+15 minutes). As is shown in Figure 1, a normal postprandial glucose excursion was observed when the insulin was taken 15 minutes prior to the meal. No postprandial excursion was observed when the insulin was taken 30 minutes prior to the meal. This is the desirable outcome in a hyperglycemic individual. Of particular interest is the fact that when the insulin lispro was taken right at mealtime (which is the most common pattern in type 1 diabetic patients), significant postprandial hyperglycemia was observed. Figure 2 provides the integrated postprandial glucose excursion (above and below baseline) over the entire 5½ hour study and reflects the data in Figure 1. This study strongly supports the injection of insulin lispro at least 15 minutes prior to the meal when premeal hyperglycemia is present.