Drug Treatments:

Introduction

In the past five years or so, the number of drug therapies for diabetes has increased substantially, with many more exciting developments in the pipeline. Insulin has been available since the 1920s, and sulfonylureas became widely used in the 1950s. Until 1995, these two drugs were the only therapies available for patients with diabetes. Since that time, several new drugs have been introduced, including thiazolidinediones, metformin, alpha glucosidase inhibitors, and repaglinide.

Insulin

Insulin is still the mainstay of diabetes therapy. This hormone is currently the drug of choice for patients with type 1 diabetes, and is also used in type 2 diabetes as well, especially when oral agents have failed. Originally derived from the pancreas of cows and pigs, virtually all insulin now in use is human insulin. Human insulin is derived from recombinant DNA techniques, which involves mass production from specially engineered bacteria (Humulin) or yeast (Novolin). It can also be created by chemically modifying beef or pork insulin (so-called "semisynthetic" insulin). Despite minor patient-to-patient variability, the source of the insulin is relatively unimportant in deciding upon the appropriate regimen for any given individual. Much more important are modifications made to insulin that change its onset, peak, and duration of action. These variations can be exploited to generate a specific regimen that will bring a patient with diabetes into the best control possible.

Insulin is a protein, which means that it cannot be taken orally without being destroyed by enzymes in the stomach and intestine. This means that it has to be injected, although new formulations of insulin with novel modes of delivery are in clinical trials.

Oral Medications

Oral medications for diabetes are available, although most of these are limited to patients with type 2 diabetes. Sulfonylureas, for example, are drugs that increase the release of insulin from the pancreas. There are several of these compounds, although most are equally effective if administered properly. A new agent called repaglinide (Prandin) has recently become available; it also works by causing insulin to be released from the pancreas. Both repaglinide and the sulfonylurea class of drugs can cause hypoglycemia and weight gain, as would be expected of any drug that increases insulin levels.

There are also new agents on the market that work via a completely different mechanism. These drugs are insulin sensitizers, and instead of causing more insulin to be released, they act on fat, muscle, and liver to allow the body's own insulin to work more efficiently. The first of these drugs to hit the U.S. market was metformin (Glucophage), a member of the biguanide class of compounds. More recently, several drugs of the thiazolidinedione class have been introduced, including troglitazone (Rezulin), rosiglitazone (Avandia), and pioglitazone (Actos). Troglitazone was subsequently pulled from the market because of a few cases of severe liver toxicity.

Finally, there are new agents that act to reduce the amount of sugar absorbed by the intestine after a meal. These drugs, called alpha-glucosidase inhibitors, can actually be used in both type 1 and type 2 diabetes. Two versions are currently on the market, including acarbose (Precose) and miglitol (Glyset).

Below we have listed all the FDA approved oral medications used for diabetes.

FDA-Approved Diabetes Drugs

Sulfonylureas:
Brand Name	Generic Name
Amaryl	glimepiride
DiaBeta	glyburide
Diabinese	chlorpropamide
Dymelor	acetohexamide
Glucotrol	glipizide
Glucotrol XL	glipizide
Glynase PresTab	glyburide
Micronase	glyburide
Orinase	tolbutamide
Tolinase	tolazamide