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Type 2 diabetes - oral medicines

Description

Insulin is a hormone produced by the pancreas to control blood sugar (glucose). Diabetes is caused by the body producing too little insulin, not using insulin properly, or both.

With type 2 diabetes, the body is resistant to insulin and doesn't use insulin as well as it should. Oral medicines can help lower blood sugar in people with type 2 diabetes.

People with type 1 diabetes must use insulin to manage their diabetes. They may also use certain oral medicines.

Alternative Names

Oral medicines for type 2 diabetes; Type 2 diabetes - oral medicines; High blood sugar - oral medicines; Type 2 diabetes and oral medicines; Oral anti-diabetes medicines

When Are Medicines Given?

Type 2 diabetes may be controlled with meal planning, weight loss, and exercise. If these steps alone are not enough, you also may need oral medicines to help keep blood sugar in your target range.

Types of Oral Medicines

Different oral diabetes medicines work in different ways to help control diabetes:

There are eight major classes of oral medicines for diabetes:

These medicines may be used alone or in combination.

BIGUANIDES

Metformin (Glucophage, Glumetza, Riomet, and Fortamet) is a biguanide. This is often the first oral medicine health care providers prescribe for type 2 diabetes.

Metformin is a medicine that stops the liver from making glucose. It also makes body tissues more sensitive to insulin.

This medicine:

There are two types of metformin:

The most common side effect of metformin is diarrhea. Sometimes people taking metformin will become deficient in vitamin B12. If you have liver or kidney disease, tell your provider. People with liver or kidney disease or who are heavy drinkers should not take metformin.

SGLT2 INHIBITORS

SGLT2 inhibitors increase the amount of glucose that goes out in the urine. They may also lead to some weight loss and lower blood pressure in people with diabetes.

SGLT2 inhibitors include:

If you have kidney disease, tell your provider before taking these medicines. Side effects include urinary tract infections and yeast infections due to the presence of more sugar in the urine.

SULFONYLUREAS

These medicines help the pancreas produce insulin and help the body use glucose (blood sugar) for energy. Sulfonylureas include:

Glipizide is taken 30 minutes before a meal. Glyburide and glimepiride are taken with meals.

In the beginning, your provider will:

When you take sulfonylureas:

The most common side effect of sulfonylureas is hypoglycemia. Other side effects include weight gain, irritability, stomach upset, and skin rashes.

Tell your provider if your weight changes or if your blood sugar level is regularly low. Your provider will adjust the dosage of the medicine.

DPP-4 INHIBITORS

These medicines help the body release more insulin. They also lower the amount of glucose made by your body. DPP-4 inhibitors help lower blood sugar without causing hypoglycemia.

DPP-4 inhibitors include:

These medicines are taken once a day. Common side effects are:

These medicines can also cause severe joint pain. If you notice joint pain, contact your provider right away.

THIAZOLIDINEDIONES (GLITAZONES)

Pioglitazone (Actos) and rosiglitazone (Avandia) are in this group of medicines. They lower insulin resistance by making body tissues more sensitive to insulin. These medicines are taken 1 to 2 times a day with or without meals.

Side effects include:

If you have heart disease or liver disease, and are prescribed a thiazolidinedione medicine, ask your provider if it is safe to take it. If you have side effects, stop taking the medicine right away and tell your provider.

ALPHA-GLUCOSIDASE INHIBITORS

These medicines delay the digestion of carbohydrates (starches and sugars) in the body. This helps lower blood sugar after a meal. Acarbose (Precose) and miglitol (Glyset) are alpha-glucosidase inhibitors.

These medicines are taken with the first bite of each meal. Side effects include bloating, flatulence, and diarrhea.

MEGLITINIDES

Meglitinides such as repaglinide (Prandin) and nateglinide (Starlix) increase insulin production in the pancreas. Avoid alcohol when you are on these medicines.

These medicines:

Side effects can include low blood sugar and stomach upset.

BILE ACID SEQUESTRANTS

These medicines lower blood sugar and cholesterol in people with diabetes. Bile acid sequestrants were originally used to treat high LDL (bad) cholesterol. These medicines also help lower blood sugar.

These medicines are often prescribed for people with type 2 diabetes who also have high cholesterol. They also may be used for people who have liver problems and can't take other medicines.

Cholestyramine (Prevalite, Questran) and colesevelam (Welchol) are bile acid sequestrants. Side effects include flatulence and constipation.

How Are These Medicines Used?

Oral diabetes medicines are often used in combination. Combining one medicine with another may give better blood sugar control than a single medicine.

It is likely that your provider will first recommend that you take metformin. If your blood sugar does not come within range in 3 months, metformin may be combined with another medicine. If your blood sugar target is still not in range after another 3 months, your provider may recommend a three-medicine combination.

Before prescribing oral medicines, your provider will consider the following:

You and your provider can discuss your options and what will work best for you.

Low Blood Sugar

Low blood sugar (hypoglycemia) is common in people with diabetes who use medicines to control their diabetes. Severe low blood sugar is a medical emergency. It can cause seizures and brain damage. Be sure to ask your provider what you should do if you have symptoms of low blood sugar.

Also, be sure you know how to tell when your blood sugar is getting too low.

When your blood sugar does get too low, follow your provider's instructions on how to treat yourself. In general, you should eat or drink something with 15 grams of carbohydrates, such as:

When to Call the Doctor

Do not stop taking diabetes medicines suddenly or change the dosage without talking with your provider. Be sure to keep your provider appointments to make sure the medicines are working well.

Contact your provider if you have any of these symptoms or side effects:

References

Ahmann AJ, Riddle MC. Therapeutics of type 2 diabetes mellitus. In: Melmed S, Auchus RJ, Goldfine AB, Rosen CJ, Kopp PA, eds. Williams Textbook of Endocrinology. 15th ed. Philadelphia, PA: Elsevier; 2025:chap 34.

American Diabetes Association Professional Practice Committee. 9. Pharmacologic Approaches to Glycemic Treatment: Standards of Care in Diabetes-2025. Diabetes Care. 2025 Jan 1;48(Supplement_1):S181-S206. PMID: 39651989 pubmed.ncbi.nlm.nih.gov/39651989/.

Dhatariya KK, Umpierrez GE, Crandall JP. Diabetes mellitus. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024;chap 210.

Review Date: 12/11/2024
Reviewed By: Sandeep K. Dhaliwal, MD, board-certified in Diabetes, Endocrinology, and Metabolism, Springfield, VA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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