Essentials of Oral Type 2 Diabetes Medications
Studies have shown that immediate initiation of medications to control blood sugars decreases the risk of long term complications. The first line recommendation for type 2 diabetes is metformin. It works by decreasing the liver’s production of glucose, decreases the absorption of glucose in the intestines and improves glucose uptake into the cells. It does not cause weight gain or low blood sugars. However, those with kidney disease, liver disease, heart failure or alcoholism should not take metformin.
Another class of oral medications is the sulfonylureas, such as glipizide and glimeperide. They are somewhat effective, lowering blood sugars up to 20% but can cause hypoglycemia or blood sugars that are too low. They work by causing the pancreas to release more insulin, improving the cell’s insulin sensitivity, and decreasing the liver’s release of glucose. Side effects include weight gain and should be used with caution in elderly patients. A group similar to the sulfonylureas is called meglitinides, including repaglinide and nateglinide. They are less likely to cause hypoglycemia but are more expensive than the sulfonylureas.
The next group are known as thiazolidinediones which include rosiglitazone and pioglitazone. Increasing insulin sensitivity is the mechanism of action, but there have been some problems associated with this class. Rosiglitazone has been removed from the market in Europe due to increased risk of heart damage. Pioglitazone may also increase the risk of bladder cancer but the FDA is awaiting further review of studies before any actions are to be made. This class if more expensive than metformin and should be avoided in heart failure patients.
Sitagliptin and saxagliptin are DPP-IV inhibitors. They increase insulin release from the pancreas therefore lowering blood sugars. They can be used as the initial treatment for diabetes but they have only mild reductions in blood sugar and are expensive. Hence, they are usually used as a second or third line of treatment.
Glucagon-like peptide 1 agonists include exenatide and liraglutide. These are injectable medications given daily or weekly. They are not insulin and should not be used alone to control diabetes. They cause an increase in the pancreatic cells that produce insulin, and slow down stomach emptying.
The last group is the alpha-glucosidase inhibitors, acarbose and miglitol. These act in the gastrointestinal system decreasing the break down and absorption of glucose. They have the unpleasant side effect of flatulence and diarrhea and therefore patient compliance is poor. In summary, most type 2 diabetics can be started on oral medications and lifestyle modifications. Initial therapy is metformin and it has benefits beyond improved glucose control, such as weight loss. Once therapy is initiated progress should be evaluated every three months and modifications made until the HgA1c is less than 7 per the American Diabetes Association (ADA) guidelines. More information can be found at the ADA website, http://www.diabetes.org.