Oral antidiabetic agents are usually continued when insulin is started, unless there are specific contraindications or substantial risks of hypoglycemia (in some cases, the dose of sulfonylureas may be decreased or discontinued).
9 This continuance of therapy helps patients avoid the loss of further glycemic control during the transition to insulin. The insulin dose should be titrated on the basis of a fasting blood glucose target. The American Diabetes Association recommends a goal of less than 130 mg/dL.
20 A patient should expect an approximately 0.5% decrease in the HbA
1c level for each insulin dose increment of 0.1 U/kg per day. Basal insulins can be self-titrated up to either a target fasting blood glucose level or an approximate dose of 0.5 U/kg per day. At higher doses, the improvement in the decrease in the HbA
1c level is less substantial, and the risk of hypoglycemia increases.
21 If, after sufficient time, the HbA
1c level still has not reached goal with the use of 0.5 U of basal insulin per kilogram per day, then attention should be focused on mealtime or prandial glucose excursions. If excursions are present, consider adding an agent to target postprandial hyperglycemia, which is the likely cause of persistent hyperglycemia. This can be confirmed by having the patient check his or her glucose level 2 hours after the meal.
22 A number of options exist for the treatment of prandial hyperglycemia, including prandial insulin (eg, a fast-acting insulin or rapid-acting insulin analog, such as insulin lispro, insulin aspart, or insulin glulisine) or an incretin-based therapy (eg, a dipeptidyl peptidase-4 [DPP-4] inhibitor [such as sitagliptin, saxagliptin, or linagliptin] or a glucagon-like peptide-1 [GLP-1] receptor agonist [such as exenatide (administered twice per day), liraglutide (administered once per day), or exenatide (administered weekly)]). Exenatide extended release is not currently approved by the US Food and Drug Administration for use with insulin therapy.