Articles

Insulin therapy in type 2 diabetes.

Author

Mudaliar S, Edelman SV.

Date

12/2001

Journal

Endocrinol Metab Clin North Am

Abstract

Type 2 diabetes is a common disorder often accompanied by numerous metabolic abnormalities leading to a high risk of cardiovascular morbidity and mortality. Results from the UKPDS have confirmed that intensive glucose control delays the onset and retards the progression of microvascular disease and possibly of macrovascular disease in patients with type 2 diabetes. In the early stages of the disease, insulin resistance plays a major role in the development of hyperglycemia and other metabolic abnormalities, and patients with type 2 diabetes often benefit from measures to improve insulin sensitivity such as weight loss, dietary changes, and exercise. Later, the use of oral insulin secretagogues and insulin sensitizers as monotherapy and in combination helps maintain glycemia for varying periods of time. Ultimately, because of the progressive nature of the disease and the progressive decline in pancreatic beta-cell function, insulin therapy is almost always obligatory to achieve optimal glycemic goals. Not all patients are candidates for aggressive insulin management; therefore, the goals of therapy should be modified, especially in elderly individuals and those with co-morbid conditions. Candidates for intensive management should be motivated, compliant, and educable, without other major medical conditions and physical limitations that would preclude accurate and reliable HGM and insulin administration. In selected patients, combination therapy with insulin and oral antidiabetic medications can be an effective method for normalizing glycemia without the need for rigorous multiple-injection regimens. The patients for whom combination therapy is most commonly successful are those who do not achieve adequate glycemic control using daytime oral agents but who still show some evidence of responsiveness to the medications. Bedtime intermediate-acting or predinner premixed intermediate- and rapid-acting insulin is administered and progressively increased until the FPG concentration is normalized. If combination therapy is not successful, a split-mixed regimen of intermediate- and rapid-acting insulin equally divided between the prebreakfast and pre-dinner periods is advised for oese patients, and more intensive regimens are advised for thin patients. Insulin therapy is invariably associated with weight gain and hypoglycemia. The use of metformin or glitazones in combination with insulin has been demonstrated to have insulin-sparing properties. Also, metformin use may ameliorate weight gain. The use of continuous subcutaneous insulin infusion pumps can be particularly beneficial in treating patients with type 2 diabetes mellitus who do not respond satisfactorily to more conventional treatment strategies. Intraperitoneal insulin delivery systems hold considerable promise in type 2 diabetes because of their more physiologic delivery of insulin and their ability to inhibit hepatic glucose production selectively, with less peripheral insulinemia than with subcutaneous insulin injections. Newer insulin analogues such as the rapidly acting Lispro insulin and the peakless, long-acting glargine insulin are increasingly being used because of their unique physiologic pharmacokinetics. New developments such as inhaled and buccal insulin preparations will also make it easier for many patients to initiate and maintain a proper insulin regimen. Finally, a new generation of gut peptides such as amylin and GLP-1 will add a new dimension to glycemic control through modification of nutrient delivery and other mechanisms; however, the ultimate goal in the management of type 2 diabetes is the primary prevention of the disease. The Diabetes Prevention Program (DPP) sponsored by the National Institutes of Health has currently randomly assigned more than 3000 persons with impaired glucose tolerance and at high risk of developing diabetes into three treatment arms: metformin arm, an intensive lifestyle-modification arm, and a placebo arm. The study will conclude in 2002 after all participants have been followed for 3 to 6 years.