After a diabetes diagnosis, it is important to start an action plan to regulate blood sugar. When diet and exercise are not enough, the next step your physician or endocrinologist will consider is oral medications.

What is the Difference Between Injectable Insulin and Oral Diabetes Medication?

When a person is diagnosed with diabetes, it is because their pancreas is not producing the hormone insulin or the body is resisting it. Insulin is an important component for the use of glucose as energy throughout the body.

Insulin is crucial in supporting healthy blood sugar levels. When blood sugar is too high, it can lead to a breakdown of fat and muscle tissue as well as dehydration. Over time, high blood glucose levels can damage the entire body from blood vessels to major organs.

A Type 1 diabetes diagnosis means that the pancreas is not producing any insulin. For this reason, a person would be prescribed insulin through injections or via an insulin pump. Insulin cannot be administered orally as the stomach enzymes will break down the insulin and reduce its efficacy.

A Type 2 diabetes diagnosis means that the body is not producing enough insulin or regulating it effectively due to poor cell response to insulin. Diet, exercise, and weight loss are important factors to keep Type 2 diabetes under control. When it is not enough, oral drugs for diabetes are then considered.

How Do Oral Diabetes Medications Work?

There are ten classes of oral diabetes medication available. Treatment options depend on the desired course of action:

  • Increase insulin secretion from the pancreas
  • Decrease glucose release from the liver
  • Decrease insulin resistance in the fat and muscle tissues
  • Slow carbohydrate digestion in the intestines
  • Remove excess sugar from the kidneys

A physician or endocrinologist must weigh the treatment options based on several factors including allergies, other long-term health conditions, risk of hypoglycemia, and the possibility of combination therapy.

Oral Diabetes Medication Classes


Sulfonylureas help the pancreas secrete more insulin.

Oral drugs in this class include  Micronase (glyburide), Glucotrol (glipizide), and Amaryl (glimepiride).

While effective for lower A1C numbers, it can cause low blood sugar levels or hypoglycemia.

Dipeptidyl peptidase 4 (DPP-4) inhibitors

DPP-4 will increase insulin secretion from the pancreas while decreasing glucose from the liver.

Oral drugs in this class include Januvia (sitagliptin) and Onglyza (saxagliptin).

Both of these medications may have side effects including headache, runny or stuffy nose, sore throat, upper respiratory infection, nausea, and upset stomach. Januvia is not recommended for patients with kidney problems as it is reported to worsen kidney function.

Alpha-glucosidase inhibitors

Alpha-glucosidase inhibitors slow the digestion of carbohydrates to reduce the rate of glucose absorption in the intestines. It does not cause low blood sugar or hypoglycemia unless combined with other medications or insulin.

Oral drugs in this class include Precose (acarbose) and Glyset (miglitol).

Side effects include diarrhea, gas, bloating, nausea, and stomach pain.


Biguanides increase insulin secretion from the pancreas while decreasing glucose from the liver. At the same time, it increases the amount of glucose absorbed by muscle cells.

Oral drugs in this class include Glucophage (metformin). Metformin can be combined with other drugs in other classes for combination therapies such as Prandimet (repaglinide and metformin).

Side effects include temporary nausea, loss of appetite, diarrhea, increased abdominal gas, and a metallic taste.


Meglitinide increases insulin secretion in the pancreas.

Oral drugs in this class include Prandin (regalinide) and Starlix (nateglinide).

The most common side effect in this class is hypoglycemia. There is also a possibility of weight gain.

Sodium-glucose transport protein 2 (SGLT2) inhibitors – work with the kidneys to remove extra sugar from the body (Jardiance (empagliflozin), Invokana (canagliflozin), Farxiga (dapagliflozin)


Thiazolidinediones make insulin more effective by decreasing insulin resistance in the tissues. This class of drugs will lower the amount of glucose released by the liver.

Oral drugs in this class include Actos (pioglitazone) and Avandia (rosiglitazone).

This class may be considered in fewer cases as it is restricted by FDA due to severe side effects such as fluid retention, worsening heart and lung disease, and liver failure

Bile acid sequestrant

Bile acid sequestrant lowers the LDL (bad) cholesterol, but may also lower blood sugar.

Oral drugs in this class include Welchol (colesevelam).

This drug should be taken with plenty of water. Side effects are generally constipation, but also heartburn, gas, bloating, diarrhea, nausea, and muscle aches and pains.

Dopamine agonist

Dopamine agonist lower glucose released from the liver and makes the insulin function better.

Oral drugs in this class include Cyclocet (bromocriptine).

Common side effects include dizziness upon starting the medication. Gastrointestinal discomfort and hypoglycemia are other possible side effects.

Glucagon like Peptide 1 (GLP-1) receptor agonist

GLP-1 slows digestion and decreases the liver’s production of glucose. It also helps the pancreas produce insulin.

Oral drugs in this class include Rybelsus (semaglutide).

This drug was initially administered via injection and only recently has been available as oral diabetes medication. Side effects include nausea, diarrhea, vomiting, indigestion, constipation, and loss of appetite.

What are the Most Common Oral Diabetes Medications?

The most common oral diabetes medication by far is metformin or Glucophage. As one of the older drugs on the market, it is considered one of the safer, more effective types of medications with fewer side effects that impact a patient’s quality of life. Metformin is also combined with other oral diabetes medications. It is often the first prescription a doctor will consider for prediabetes and Type 2 diabetes.

Sulfonylureas are also more commonly prescribed oral drugs for diabetes though there is a greater concern for low blood sugar or hypoglycemia.

When a doctor prescribes any oral drugs for diabetes, it is important to follow the dosage directions. Some drugs are taken with the first meal of the day while others do not need to be taken with food. It is helpful to remember to take oral diabetes medication with food.

Are Oral Diabetes Medications Acceptable for Pregnant Mothers?

Gestational diabetes affects approximately 7% of pregnant women in the United States. Even though it typically goes away after birth, there is a chance of developing type 2 diabetes in the future.

Diet and exercise along with more frequent prenatal visits are part of a care plan after a gestational diabetes diagnosis. If further treatment is required, insulin injections are more likely to be prescribed rather than oral medications for the safety of the baby and mother.