Diabetes Mellitus: Treatment

Dietary and lifestyle interventions are important for patients with all types of DM (see below). Education for diabetes self–management, which includes self–monitoring of blood glucose, is an important component of treatment.⁷

Type 1 Diabetes

Insulin is available in several forms, which differ in duration of action.

• Long-acting insulin, such as insulin glargine (Lantus) or insuline detemir (Levemir), can be administered once a day, though some may require injections with these insulins twice daily.
• Regular insulin or fast–acting insulin analogs are short–acting and can be administered before meals to curb postprandial blood glucose elevations.
• NPH has an intermediate length of action and is often administered in the morning and evening. NPH and regular or fast–acting insulin come in premixed ratios such as 70%:30% and 50%:50% for convenience when both insulin types are required. These premixed insulins are primarily used in patients with type 2 diabetes.
• Fast–acting inhalable insulin was approved for use in adults in 2006. Its long–term safety remains unclear, particularly with regard to respiratory health.

Amylin is a beta–cell hormone that is co–secreted with insulin. Pramlinitide, a synthetic amylin analog, is injected at mealtimes along with fast–acting insulin. It reduces postprandial rises in blood glucose concentrations and suppresses appetite, which may lead to weight loss.

Type 2 Diabetes

Biguanides. Metformin is commonly used as a first–line agent. It decreases hepatic gluconeogenesis and increases insulin sensitivity. It is contraindicated in heart failure, renal insufficiency, liver disease, serious infection and illness, and other disease processes.

Sulfonylureas. Glipizide, glyburide, and glimepride are the most commonly used oral antihyperglycemic medications. Glyburide is taken twice a day and may be less desirable for geriatric patients. Glipizide (Glucotrol or Gluctrol XL) and glimiperide (Amaryl) are longer acting, and these should be used cautiously in the elderly and those with any renal insufficiency. Sulfonylureas may cause hypoglycemia.

Thiazolidinediones. Pioglitazone and rosiglitazone increase insulin sensitivity, decrease glucose production, and may also increase insulin secretion. These insulin sensitizers have been

Meglitinides. Nateglinide and repaglinide stimulate insulin secretion, but are shorter acting than sulfonylureas and must be taken with meals.

Alpha–glucosidase inhibitors. Acarbose and miglitol inhibit the conversion of carbohydrates to monosaccharides, and lower postprandial glucose values. Flatulence is a common side effect and may limit compliance, but it generally improves over time.

Incretin Mimetic. Exenatide is an injectable synthetic used to increase insulin secretion at mealtime. It is less likely to cause episodes of low blood sugar or weight gain, compared with insulin or insulin secretogogues. 

A patient with presumed type 2 diabetes and autoantibodies is less likely to respond to the above agents. Such patients may require insulin therapy and are at increased risk of ketoacidosis.

Gestational Diabetes           

Dietary intervention is the first–line treatment for GDM. Adequate control is achieved if fasting plasma glucose is less than 90 mg/dL and 1–hour postprandial glucose is less than 120 mg/dL. When these goals are not met, insulin should be considered. Dietary interventions are discussed in detail under Nutritional Considerations.

Insulin is the best–studied pharmaceutical agent for GDM and the only recommended treatment in the United States. However, metformin and glyburide are used by some obstetricians with some evidence of safety. 

For all types of diabetes, good blood–glucose control decreases the risk of complications. Patient medications should be frequently reviewed, because certain pharmaceuticals, such as beta–blockers, thiazides, oral contraceptives, and glucocorticoids, can impair glucose tolerance.

A1c testing should be used as an index of diabetes control. It provides a fairly accurate measurement of the average blood glucose during the previous 2 to 3 months. The A1c goal set by the American Diabetes Association is 7%. However, this value is not a threshold. Risk of complications appears to fall with lower A1c values, and many clinicians aim for an A1c of less than 6.5% through dietary and lifestyle modifications and medications as needed.

Role of Exercise

A sedentary lifestyle is associated with increased risk for impaired glucose tolerance and diabetes.⁹ Exercise¹⁰ and diet–exercise programs that produce weight loss significantly reduce the risk for type 2 diabetes.^11,12

Exercise alone has little or no effect on body weight.¹³ However, in persons with established diabetes, exercise reduces blood glucose and plasma lipid concentrations¹⁴ and improves insulin sensitivity. Exercise also reduces cardiovascular complications of diabetes, including high blood pressure, left ventricular diastolic function, arterial stiffness, systemic inflammation, and left ventricular mass.¹⁵

Women who either have or are at risk for gestational diabetes can also benefit from exercise. Walking or upper–body exercises (but never in a supine position) may reduce the risk of gestational diabetes¹⁶ and help lower glucose levels to the normal range. In women with GDM, exercise has been found to be a useful strategy for helping to maintain blood glucose within the normal range and to control blood glucose without the use of insulin.¹⁷ Note: Exercising must be stopped if contractions occur.