Insulin, at one time, was the only drug available to treat diabetes. Today there are many different classes of drugs which are often used together, although sorting through the different classes can be confusing.
Diabetes occurs when your pancreas doesn’t manufacture enough insulin or none at all.
In your body, insulin is used to metabolize sugars or glucose. Without insulin, therefore, your blood glucose rises, which means the circulating glucose causes damage, most notably to your large and small blood vessels.
Ideally, you want to replace the insulin and/or increase the effectiveness of any insulin your pancreas is able to produce. Obviously, insulin injections do just that.
The variety of insulins today ranges from short-acting to long-acting, and they are used to mimic as closely as possible your body’s natural production of insulin.
At one time insulin was saved for when your pancreas did not produce any insulin, but now insulin is used in combination with oral tablets and much earlier, even when your pancreas is still producing some insulin.
Oral diabetes medications are most commonly given in combination, with two or more different types of drugs used to enhance the effectiveness of overall treatment.
Metformin is given with food. It enhances the effects of insulin, but it can cause stomach upset. Sulfonylureas (i.e. SUs), for example gliclazide, glyburide, act in the pancreas to stimulate insulin production. The risk of hypoglycemia or too-low blood glucose is high with the SUs, and is often the reason for stopping them.
Metformin and SUs are often the first drugs used to treat diabetes, and they have been available for the longest.
To understand some of the other drugs, you need to know about incretins. These are substances in the body that stimulate the pancreas to release insulin. You want to have more incretins and that is what both dipeptidyl peptidase-4 or DPP-4 inhibitors and glucagon like peptide-1 or GLP-1 receptors agonists do.
The DPP-4 agents like linagliptin, sitagliptin, and saxagliptin inhibit enzymes that break down incretins; the GLP-1 agents like dulaglutide, exenatide, and liraglitide activate incretin pathways. One drawback with the GLP-1 agents is that they are injectable.
The sodium glucose-linked transporter 2 or SGLT2 drugs enhance your body’s ability to excrete excess glucose in the urine, for example canagliflozin, dapagliflozin, and empagliflozin. Unfortunately, with extra glucose being excreted in your urine, you increase your risk for urinary and vaginal infections. Often, these drugs are prescribed along with treatments for yeast infection, just in case!
There are several other glucose-lowering drugs. Alpha glucosidase inhibitors like acarbose stop enzymes that break down complex carbohydrates into simpler glucose molecules which means glucose doesn’t get absorbed to raise blood glucose. Pioglitazone is a thiazolidinedione or TZD which enhances insulin sensitivity, but has potential cardiovascular effects. Repaglinide is a meglitinide whose action is similar to SUs, but less effective.
If you have diabetes, you may take a combination of these various agents, but remember that lifestyle changes are important no matter what drugs you may take. You want to eat healthy, lose weight, exercise, reduce alcohol consumption, and quit smoking.