Insulin therapy pharmacology

Vora, J. P., and Owens, D. R, 1991, Future trends in insulin therapy Clinical implications of novel insulin analogues and nasal administration of insulin, in Pharmacology of Diabetes. Present Practice and Future Perspectives (C. E. Mogensen and E. Standi, eds.), de Gruyter, Berlin, pp. 39-56. 

Medical nutrition therapy is recommended for all patients. For individuals with type 1 DM, the focus is on regulating insulin administration with a balanced diet to achieve and maintain a healthy body weight. A meal plan that is moderate in carbohydrates and low in saturated fat, with a focus on balanced meals is recommended. In addition, patients with type 2 DM often require caloric restriction to promote weight loss. Bedtime and between-meal snacks are not usually needed if pharmacologic management is appropriate. 

For persons with type 1 diabetes, insulin replacement therapy is necessary to sustain life. Pharmacologic insulin is administered by injection into the subcutaneous tissue using a manual injection device or an insulin pump that continuously infuses insulin under the skin. Interruption of the insulin replacement therapy can be life-threatening and can result in diabetic ketoacidosis or death. Diabetic ketoacidosis is caused by insufficient or absent insulin and results from excess release of fatty acids and subsequent formation of toxic levels of ketoacids. 

For the first time in history there was clear, unambiguous clinical evidence, in humans, that symptoms of diabetes mellitus could be controlled with the exogenous administration of the active factor of the pancreas—insulin. Thus, replacement therapy with the newly discovered hormone, insulin, had arrested what was clearly an otherwise fatal metabolic disorder. From that point forward, diabetes mellitus (type 1) became a manageable disease by pharmacological intervention. 

Although replacement therapy is basically limited to endocrine disorders, it still plays an important therapeutic role in clinical pharmacology. The number of people requiring replacement therapy for diabetes and hypothyroidism alone makes insulin and thyroid hormone among the most commonly prescribed drugs in the United States. For example, the drug Synthroid is taken daily by 8 million people to correct hypothyroidism, and its share of the market is worth 600 million per year. As more information is discovered about the role of other endogenous substances in the body, new examples of replacement therapy will occur. 

Knowledge of the patient s quantitative and qualitative meal patterns, activity levels, pharmacokinetics of insulin preparations, and pharmacology of oral antidiabetic agents for type 2 DM are essential to individualize the treatment plan and optimize blood glucose control while minimizing risks for hypoglycemia and other adverse effects of pharmacologic therapies. 

Pharmacologic therapy for acromegaly should be considered when surgery and irradiation are contraindicated, when rapid control of symptoms is needed, or when other treatments have failed to normalize growth hormone (GH) and insulin-like growth factor-1 (IGF-I) concentrations. 

Pharmacologic therapies include drugs that elicit an increase in insulin secretion in order to maximally stimulate desensitized receptors (e.g.. sulfonylureas). and drugs that alter glucose utilization or production (e.g., biguanides, troglitazone), or alter the breakdown of carbohydrates (e.g., acarbose). 

---