Insulin deficiency with and without glucagon: A comparative study between total pancreatectomy and type 1 diabetes

AIMS/INTRODUCTION: Patients with a total pancreatectomy and type 1 diabetes are similar in regard to absolute insulin deficiency, but different in regard to glucagon, providing a unique opportunity to study the contribution of glucagon to glucose metabolism in an insulin‐dependent state. The aim of the present study was to investigate the contribution of glucagon to glucose homeostasis in complete insulin deficiency in vivo. METHODS: A total of 38 individuals with a complete lack of endogenous insulin (fasting C‐peptide <0.0066 nmol/L) and whose glycemic control was optimized with an insulin pump during hospitalization were retrospectively studied. The basal insulin requirement, time‐to‐time adjustment of the basal insulin infusion rate, prandial insulin requirement and fasting plasma glucagon were compared between patients with a total pancreatectomy (n = 10) and those with type 1 diabetes (n = 28) after achievement of optimal glycemic control. RESULTS: Total daily insulin (P = 0.03) and basal insulin (P = 0.000006), but not prandial insulin requirements, were significantly lower in total pancreatectomy patients than in type 1 diabetes patients. The basal percentage (basal insulin/total daily insulin) was also significantly lower in total pancreatectomy patients than in type 1 diabetes patients (15.8 ± 7.8 vs 32.9 ± 10.1%, P = 0.00003). An increase in the insulin infusion rate early in the morning was not necessary in most patients with a pancreatectomy. The fasting plasma glucagon concentration was significantly lower in total pancreatectomy patients than in type 1 diabetes patients (P = 0.00007), and was positively correlated with the basal insulin requirement (P = 0.038). CONCLUSIONS: The difference in insulin requirements between total pancreatectomy and type 1 diabetes patients suggests a contribution of glucagon to the basal insulin requirement and dawn phenomenon.