Blood Glucose – Lowering Medications and Insulin

Today, there are a variety of categories of medications available to help lower blood glucose. Each category of medicines works in different ways. All people with type 1 diabetes require insulin, whether they get it by injection or an insulin pump. Most people with type 2 diabetes need to take one or more medications. Which medications you take and how many generally depends on the number of years you’ve had type 2 diabetes, how well you’ve cared for it, and how successful you’ve been in making lifestyle changes. All of these medication options allow you and your health care providers to find the approach that most closely matches your diabetes and lifestyle needs.

If you are taking insulin, either through multiple daily injections or an insulin pump, advanced carb counting will help you calculate your insulin doses and keep your blood glucose levels on target. Here’s a review all of the available medication options, how they work, and what things you need to consider when taking them.

There are two basic categories of diabetes medications: oral medications and injectable medications. These medications use different mechanisms to help lower blood glucose levels, such as increasing insulin production, reducing insulin resistance, and/or reducing glucose absorption. Insulin is injected into the body when the pancreas cannot produce any or enough insulin to control your blood glucose. People with type 1 diabetes use insulin from the time of diagnosis, and about 50-60% of people with type 2 diabetes eventually need to take insulin along with other medications to control their blood glucose levels.

Oral Medications

Oral medications include several different classes of drugs, including sulfonylureas, meglitinides, biguanides, thiazolidinediones, alpha-glucosidase inhibitors, DPP-4 inhibitors, bile acid sequestrants, and dopamine agonists.

• Sulfonylureas have been around since the 1950s. They stimulate certain cells I the pancreas, called beta-cells, to release more insulin, which lowers blood glucose levels. These can only work if you still make some insulin.
• Meglitinides also stimulate the beta-cells in the pancreas to release more insulin.
• Biguanides (metformin) lower blood glucose levels by reducing the amount of glucose produced by the liver. They also make muscle tissue more sensitive to insulin, so glucose can be absorbed. Metformin, now a generic medication, is today the most commonly used starting medication for people with type 2 diabetes.
• Thiazolidinediones (sometimes called glitazones) reduce the amount of glucose produced by the liver and help insulin work better in muscle and fat. Recent studies have shown that this class of medication may increase the risk of heart failure and bone fractures in some people, so be sure to discuss this with your health care team if you take a thiazolidinedione.
• Alpha-glucosidase inhibitors slow the breakdown of starches, such as bread, potatoes, and pasta, in the intestine. This slows the rise in blood glucose levels after a meal.
• DDP-4 inhibitors help slow the breakdown of a naturally occurring compound in the body, called glucagon-like peptide-1 (or GLP-1). GLP-1 normally lowers blood glucose levels in the body by inhibiting the release of glucagon from the pancrease, increasing the release of insulin, and slowing the speed of digestion. People with type 2 diabetes have been found to be deficient in GLP-1 and other so-called incretin hormones. DPP-4 inhibitors slow the breakdown of GLP-1. This allows it to work longer in order to complete its normal functions.
• Bile acid sequestrants have only recently been identified in the treatment of diabetes. Colesevelam is the only FDA-approved medication from this class. It is primarily used to lower LDL (or “bad”) cholesterol, but when it is combined with a sulfonylurea regimen, it has been found to lower blood glucose levels.
• The dopamine agonist bromocriptine was approved by the FDA for treatment of type 2 diabetes in 2009. An older version of this drug was used in higher doses to treat Parkinson’s disease, but studies have shown that it can also be used to lower blood glucose levels.

Injectable Medications

Injectable medications include an amylin analog, incretin mimetics, and, of course, insulin.

• The amylin analog pramlintide is a synthetic form of the hormone amylin, which is also produced in the pancreatic beta-cells and is secreted with insulin. Amylin works with insulin and glucagon (another hormone) to maintain blood glucose levels. People with diabetes are amylin deficient. Pramlintide injections have been shown to lower blood glucose levels without causing hypoglycemia or weight gain.
• Two incretin mimetics are approved by the FDA: exenatide and liraglutide. Incretin mimetics, also called GLP-1 analogs, stimulate insulin secretion and decrease glucagon release from the beta-cells in the pancreas. They also lower the rise of glucose after eating. With these actions, incretin mimetics decrease appetite and food intake and have shown some success in helping people lose some weight.


Insulin is classified by how quickly or how long it works in the body. You’ll hear insulin referred to as rapid acting, short acting, intermediate acting, and long acting. This refers to how long it takes for the medicine to have an effect on blood glucose and how long the effect lasts. Note that all insulins can cause hypoglycemia.

How much insulin do you need?

Unfortunately, there’s no simple answer to this question. There are many ifs, ands, and buts. Health care providers have a variety of ways of deciding starting insulin doses. Even more, insulin needs can change as you move through different phases of your life or make changes in your routine. For example, women have different insulin needs in different phases of their menstrual cycle or in different trimesters of pregnancy. A man in retirement who gets into long-distance bicycling will have different insulin needs than he did before starting his new hobby. Adolescents during growth spurts have varying insulin needs.

Keep in mind that a starting dose of insulin is just that – a place to start. The next step is to use your records to fine-tune your insulin needs based on your blood glucose results. However, it’s always best to start conservatively, whether you’re just starting on insulin or moving from insulin by injection to an insulin pump. Better to be safe (and not increase the risk of hypoglycemia) than sorry.

What’s the difference between rapid-acting and short-acting insulin?

As you might guess, rapid-acting insulin works more quickly than short-acting insulin, which is known as regular insulin. The beauty of rapid-acting insulin is that the peak of its action is more likely to coincide with the rise in blood glucose from the food you’ve eaten – in about one to two hours. As the carbohydrate raises your blood glucose, the rapid-acting insulin is beginning to lower your blood glucose. Regular insulin doesn’t peak until three to four hours after the meal and can miss the mark, so to speak. Experts agree that the rapid-acting insulins aren’t even as rapid as people need to control after-meal blood glucose rises. Drug development is ongoing to find even faster-acting insulins. In the meantime, it’s best to take the rapid-acting insulin 15 minutes prior to eating, when possible.

Know your medications

It is important that you know the type of blood glucose-lowering medications(s) you take, when to take each one, how they work to help control blood glucose, and how the medication works in conjunction with the carbohydrate you eat to control your blood glucose. Talk with your diabetes care providers to make sure you have all of the information you need. Be sure to record the type, dose, and timing of each medication daily. You can record it along with your blood glucose results and your food diary, or you may use another form. Whatever method you choose, this information will help you and your health care providers interpret your blood glucose results.

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