Cardiovascular disease remains the leading cause of death for subjects with diabetes mellitus. An area of particular concern is hypoglycaemia and there is increasing evidence that iatrogenic hypoglycaemia is linked to adverse cardiovascular outcomes. There has been interest in exploring an association between hypoglycaemia and prolongation of ventricular repolarisation (or QTc on the electrocardiogram). Most of the studies to date have explored insulin-induced hypoglycaemia. Sulfonylurea therapy is also associated with an increased risk of hypoglycaemia. However, the relationship between sulfonylurea-related hypoglycaemia and ventricular repolarisation has not been extensively explored.
A single centre observational study of sulfonylurea-treated type 2 diabetes mellitus (T2DM) subjects under free-living conditions was undertaken. The aim was to explore short-term cardiovascular effects of spontaneous iatrogenic hypoglycaemia. Forty-eight hours of concurrent continuous glucose monitoring (CGM) and ambulatory electrocardiography data were obtained for 30 study participants (12F/18M; age 66.7±8.6 years; HbA1c 6.9±0.9%). Fifteen hypoglycaemic episodes (blood glucose level [BGL]
Hypoglycaemia is frequently asymptomatic and a relatively common occurrence in well-controlled, sulfonylurea-treated, T2DM subjects. Increased CV of BGL measurements may be used as a marker of increased risk of hypoglycaemia. Sulfonylurea-related hypoglycaemia, but not GV, may be associated with QTc prolongation in some subjects but there is considerable heterogeneity in individual response.