Blood glucose excursions in 3 hypothetical patients who have the same mean blood glucose concentration of approximately 200 mg/dL (11.1 mmol/L, equivalent to an A1C value of approximately 8.2%) but who have different overall blood glucose control. Patient B (solid blue curve) has relatively small variations during the day and on different days; this patient should have little difficulty in lowering daily mean blood glucose concentrations without inducing hypoglycemia. In comparison, patient A (dotted purple curve) has marked blood glucose variations on the same day, and patient C (dashed green curve) has marked blood glucose variations on different days. These aspects of blood glucose control must be improved before the mean blood glucose concentration can be safely lowered. Increasing the intensity of insulin therapy can precipitate hypoglycemia in patients A and C since many of their blood glucose values are already in the low-normal range.
