Glucose counterregulation in Type 2 diabetes mellitus

Glucose counterregulatory failure and hypoglycaemia unawareness frequently complicate treatment of Type 1 diabetes mellitus, especially when aiming fo r intensive metabolic control. Since tight metabolic control reduces microv ascular long-term complications in Type 2 diabetes mellitus, the integrity of glucose counterregulation in Type 2 diabetic patients is important. Usin g a Medline search, we identified 12 studies in which counterregulatory res ponses to insulin-induced hypoglycaemia were compared between Type 2 diabet ic patients and appropriate controls. A review of these studies showed that some patients with Type 2 diabetes mellitus develop mild counterregulatory dysfunction and reduced awareness of insulin-induced hypoglycaemia. Some s tudies suggested an association between counterregulatory impairment and in tensity of metabolic control. We speculate that the relatively low frequenc y of (severe) hypoglycaemic events in Type 2 diabetes may explain why gluco se counterregulation remains unaffected in most patients. We hypothesize th at residual Beta-cell reserve and insulin resistance provide protection aga inst severe hypoglycaemia and limit impaired counterregulation.