Individualized Glycemic Goals and an Expanded Classification of Severe Hypoglycemia in Diabetes

The view that a hemoglobin A_1c (A1C) level <7% (55 mmol/mol) is the accepted glycemic goal for most people with diabetes sometimes conflicts with the view that glycemic goals should be individualized and, thus, that somewhat higher A1C levels are appropriate for some, particularly many at risk for iatrogenic hypoglycemia because of treatment with insulin, a sulfonylurea, or a glinide. The relationship between A1C and chronic complications of diabetes is curvilinear, A1C is a relatively weak predictor of cardiovascular disease, and minor elevations of A1C above 7% have not been found to be associated with increased mortality. Iatrogenic hypoglycemia causes recurrent morbidity in diabetes and is sometimes fatal. In those at risk for hypoglycemia, a reasonable individualized glycemic goal is the lowest A1C that does not cause severe hypoglycemia and preserves awareness of hypoglycemia, preferably with little or no symptomatic or even asymptomatic hypoglycemia, at a given stage in the evolution of the individual's diabetes. A somewhat higher A1C level is appropriate in those who have previously experienced hypoglycemia or have potential high risk for hypoglycemia, have a long duration of diabetes, and have a short life expectancy, among other traits. Given the importance of severe hypoglycemia in selecting glycemic goals, it is proposed to expand the classification of severe hypoglycemia beyond a hypoglycemic event requiring assistance from another person to include a measured glucose concentration <50 mg/dL (2.8 mmol/L), a level associated with sudden death.