Treatment with insulin lispro changes the insulin profile but does not affect the plasma concentrations of IGF-I and IGFBP-1 in type 1 diabetes.

OBJECTIVE: IGF-I levels in patients with type 1 diabetes without endogenous insulin production are low. Our aim was to examine whether the plasma insulin profile obtained by treatment with the insulin analogue lispro has a different effect on plasma concentrations of IGF-I and IGFBP-1 than that seen during treatment with conventional human insulin (regular insulin). DESIGN AND PATIENTS: Twelve patients with type 1 diabetes, age 47.8 +/- 2.4 years (mean +/- SEM), body mass index 26.5 +/- 1.0 kg/m2, diabetes duration 30.5 +/- 3.2 years participated in this open label randomized cross-over study. IGF-I and IGFBP-1 levels were measured at the end of 6 weeks treatment with each insulin being administered by a continuous subcutaneous insulin infusion. IGF-I was measured fasting while IGFBP-1, free insulin and blood glucose were measured fasting and repeatedly after a morning meal preceded by an insulin bolus dose. RESULTS: Lispro gave a marked insulin peak of 135 +/- 20 pmol/l 50 minutes after injection. After an initial rapid rise, human regular insulin reached a plateau of approximately 50 pmol/l. The plasma free insulin area under the curve (AUC) from 0710 h to 0910 h was more than twice as large on lispro as on regular insulin (P = 0.01). Plasma IGF-I concentration was 78.8 +/- 10.9 microg/l on lispro and 82.3 +/- 10.5 microg/l on human regular insulin (not significant). AUC for IGFBP-1 did not show a significant difference even when divided from 0710 h to 0910 h and from 0930 h to 1430 h. Blood glucose AUC after administration of the bolus was significantly lower during treatment with lispro (P = 0.006) but glycosylated haemoglobin (HbA1c) was 6.4 +/- 0.2% on both therapies. CONCLUSIONS: Our results indicate that the effect of lispro on IGF-I and IGFBP-1 in patients with type 1 diabetes does not differ from that of human regular insulin.

The snack is critical for the blood glucose profile during treatment with regular insulin preprandially.

OBJECTIVES: To evaluate how a snack influences the blood glucose profile during treatment with preprandial regular human insulin. DESIGN: In a randomized study a mid-morning snack either was or was not served. Insulin was given 30 min before the usual breakfast of the patients. Plasma free insulin and blood glucose were repeatedly determined for 5 h. SETTING: Outpatient clinic at a university hospital. SUBJECTS: Twenty patients with type 1 diabetes treated with multiple injections of regular insulin (Actrapid) and eight non-diabetic subjects. INTERVENTIONS: A mid-morning snack either was or was not served 2 h after the usual morning insulin injection. MAIN OUTCOME MEASURES: A difference in the blood glucose profile after a mid-morning snack. RESULTS: With a snack there was no difference in blood glucose fasting and at 12.30 h, whilst without a snack there was a decrease of almost 4 mmol L-1, several patients experienced low blood glucose and three had hypoglycaemia. An extended peak of free insulin was reached 30 min after the insulin injection with a slow decrease to the fasting level after 5 h. After the insulin injection a significant decrease in blood glucose occurred within 30-45 min. CONCLUSIONS: A snack 2 h after the insulin injection results in a smoother blood glucose profile and reduces the risk of hypoglycaemia in patients with type 1 diabetes treated with preprandial regular human insulin. Furthermore, the recommended interval of 30 min between insulin injection and a meal may be too long.