GCG and Hypoglycemia: Of these responses, glucagon secretion from pancreatic α-cells typically increases dramatically when glucose reaches ∼3.6 mmol/L, and this response plays a primary role in preventing hypoglycemia overnight, during exercise and between meals by stimulating up to 90% of hepatic glucose output, with catecholamines and other counterregulatory hormones serving as second-line defences (Rivera et al., 2010).