The role of basal insulin therapy in patients with type 2 diabetes mellitus

Abstract

Background: The natural course of type 2 diabetes mellitus (DM) is characterized by insulin resistance followed by a progressive decline in β-cell function, which results in relative insulin deficiency. At diagnosis, a patient with tvpe 2 DM has only 50%, of β-cell function remaining. Given this inevitable decline in β-cell function and insulin secretion, most patients with type 2 DM will require insulin therapy at some point. Objective: The objective of this article was to provide a brief overview of physiologic insulin secretion and to discuss the role of basal insulin therapy in patients with type 2 DM. Methods: Materials for this article were identified through searches (2000–2005) of MEDLINE and Google, as well as from the author's personal files. Search terms included basal insulin, titration, hypoglycemia, glycemic control, and basal-bolus therapy. Results: The cfficacy of insulin either as nmonotherapy or in combination with oral agents in type 2 DM is well established. Insulin therapy has also been show to improve insulin sensitivity and, in some cases, reverse insulin resistance, possibly by elimination of glucose toxicity. In recent years, the availability of insulin formulations with more favorable pharmacokinetic profiles has reduced concerns about hvpoglycemia and weight gain, facilitating the use of insulin in patients with type 2 DM. For insulin-naive patients who are inadequately controlled on oral antidiabetic drugs, the addition of a single basal insulin dose at bedtime has been found to reduce glycosylated hemoglobin (A1C levels,with a low risk of nocturnal hypoglycemia. Basal insulins. (ie, glargine, detemir) have also been shown to induce less weight gain a significant concern for both patients and providers. The use of long-acting basal insulins may also reduce intrapatient variability in fasting blood glucose values. Moreover, the long-acting basal insulins such as glargine and detemir can be administered QD, which may enhance the potential for patient compliance. Aggressive titration of insulin doses based on a target fasting plasma glucose level of 100 to 120 mg/dL is essential to achieving target A1C levels (<7.0%,). As β-cell function declines, patients may require switch to basal-bolus insulin therapy. Although the long- and intermediate-acting insulin formulations are comparable with regard to efficacy as the basal component in basal-bolus therapy, the long-acting insulins have been associated with lower rates of nocturnal hypoglycemia, which can have a positive effect on glycemic control during the daytime. Conclusion: Basal insulins, both intermediate- and long-acting formulations, are playing an increasingly important role in the treatment of type 2 DM.