Many clinicians perceive the risk of severe hypoglycaemia as firmly tethered to the level of glucose control: the tighter the control, the greater the risk. This perception has its roots in the historical association between A1C and hypoglycaemia risk, established in several studies. As a frequently cited example, the DCCT trial found a 3-fold increased risk of severe hypoglycaemia in patients randomized to the intensive management arm of the study.
Iatrogenic hypoglycaemia is the limiting factor in the glycaemic management of diabetes, particularly with insulin. That hypoglycaemia can kill experimental animals has been known since the discovery of insulin. There are now numerous reports of deaths of patients with diabetes associated with hypoglycaemia. Since hypoglycaemia can kill, and hypoglycaemia at the time of death has been documented by continuous glucose monitoring in a patient with diabetes, it is reasonable to conclude that these are causal associations.