In the general population, altered glucose metabolism is associated with deleterious microvascular changes, inflammatory cardiovascular disease and death. Large population studies have established clinically relevant glucose threshold levels associated with these risks. These have led to the currently accepted definitions of diabetes and oral glucose tolerance abnormalities as well as recommendations for treatment. While these same definitions and treatment recommendations may be appropriate to prevent microvascular disease in those with cystic fibrosis (CF), they may be inadequate when it comes to preventing the major complications of diabetes in CF—namely, respiratory failure and death.

CF-related diabetes (CFRD) is primarily caused by insulin insufficiency as a result of pancreatic fibrosis and islet destruction. In addition, there is a variable component of insulin resistance related to underlying chronic inflammation superimposed with bouts of acute infection. Patients with CFRD are at risk of typical diabetic microvascular complications which, although they occur less frequently and may be less severe than in other diabetes populations, are similarly related to duration of diabetes and the level of glycaemic control.1 In contrast, macrovascular disease—the primary cause of mortality in the general diabetes population—is not known to occur in CFRD, perhaps at least in part because cholesterol levels are low. However, CFRD is associated with its own unique morbidity and mortality profile which has been explored in detail in a recent technical review.2

A number of studies have documented worse survival in …