There has been a veritable explosion of new oral medications to help control blood glucose levels in people with type 2 diabetes. But the number of diabetes medications can cause confusion over which ones to take. Your doctor can help you choose the right medication, based on your own particular needs. To help in this important decision, Johns Hopkins provides an overview of the broad categories of diabetes medications.

At least 21 different diabetes medications are now on the market; in addition, weight loss medications can also help lower your blood glucose if you lose weight. And all the medications show better effects when combined with a healthy lifestyle, meaning that simply taking pills is not enough.

Various types of oral diabetes medications work to control blood glucose levels in different ways:

Sulfonylureas and short-acting sulfonylurea-like medications all stimulate cells in the pancreas to release more insulin. Sulfonylureas (such as glimepiride [Amaryl], glipizide [Glucotrol, Glucotrol XL], and glyburide [Dia- Beta, Micronase, Glynase]) are the oldest class of diabetes medication.

Short-acting sulfonylurealike medications (nateglinide [Starlix], repaglinide [Prandin]) are used immediately before meals. Hypoglycemia and weight gain are the main side effects of all these medications, because they stimulate insulin secretion.

Metformin (Glucophage, Glucophage XR, Glumetza) is a venerable diabetes medication used around the world since the 1960s and in the United States since the 1980s. The most widely prescribed pill to control blood glucose, metformin works primarily by decreasing the liver’s production of glucose as well as increasing the amount of glucose that is transported into cells.

The main side effects, which happen in about 15% of people, are bloating, loose stools, and diarrhea. Also, individuals with a number of conditions, such as kidney disease or heart failure, and even those facing elective surgery should not use metformin.

Alpha-glucosidase inhibitors such as acarbose (Precose) and miglitol (Glyset) slow the breakdown of starches and certain sugars, which help keep glucose levels from spiking after a meal. These medications often cause unpleasant gas and gastrointestinal upset.

Thiazolidinediones, one of the newer classes of pills, lower insulin resistance by helping insulin work better in muscle and fat. The two available forms are rosiglitazone (Avandia) and pioglitazone (Actos). Side effects of both include fluid retention and weight gain. Recent evidence indicates that they also increase the risk of heart failure and, possibly, heart attacks.

Dipeptidyl peptidase-4 (DPP-4) inhibitors are the newest class of treatments that boost insulin levels after blood glucose rises. The most recently approved drug, sitagliptin (Januvia), is a DPP-4 inhibitor that works by prolonging the action of hormones, called incretins, which help increase insulin production and release. The medications are new, but so far they seem to be free of major side effects.

Combination products that contain medications from different classes in one pill include pioglitazone/metformin (Actoplus Met), rosiglitazone/glimepiride (Avandaryl), metformin/glyburide (Glucovance), and metformin/ glipizide (Metaglip).

Oral diabetes medications help to control blood glucose levels when diet and exercise fail to do so alone. But they should not be seen as replacing these measures. In a recent review of nearly 17 studies that followed more than 8,000 people with impaired glucose tolerance, lifestyle interventions were at least as effective in preventing or delaying type 2 diabetes as drug treatments.