In May 2020, the Food and Drug Administration (FDA) recommended that some makers of extended-release metformin remove some of their tablets from the market in the United States. This is because some extended-release metformin tablets contained an unacceptable level of a probable carcinogen or cancer-causing agent. If you currently take this drug, call your doctor. They will advise whether you should continue to take your medication or whether you need a new prescription.

Diabetes occurs when insulin in the body cannot control blood sugar levels effectively. To help manage this, a person may need to use insulin or other drugs, such as metformin.

There are two main types of diabetes. People can treat type 1 diabetes with insulin injections and need careful diet and activity planning to avoid treatment complications.

A person can manage type 2 diabetes with lifestyle measures and oral and injectable medications, as well as insulin if other treatments are not successful.

There are so many medications available for diabetes that it can be difficult to know which is best for each person. This article will explain the different types of medication available and their effects on the body.

An insulin pen against a black backgroundShare on Pinterest
Science Photo Library/Getty Images

Treatment for type 1 diabetes always involves insulin. This replaces absent insulin in the body and keeps blood sugar levels steady.

People can self-inject insulin, or, if a person is hospitalized, a doctor might inject insulin directly into the person’s blood. Insulin is also available as a powder that people can breathe in. Some people prefer to use insulin pumps, which are small devices that send insulin through tubes inserted into the skin.

Insulin injections vary in terms of how quickly they act, their peak action, and how long they last. The aim is to mimic how the body would produce insulin throughout the day to promote efficient energy intake.

There are several types of insulin.

Rapid-acting injections

These injections take effect within 5–15 minutes but last a relatively short time of 2–4 hours. Types of rapid-acting injections include:

Short-acting injections

These take effect within 30–60 minutes and last 3–6 hours. They consist of regular insulin (Humulin R and Novolin R).

Intermediate-acting injections

These medications take effect within 2–4 hours, last 12–18 hours, and include insulin isophane, also called NPH insulin (Humulin N and Novolin N).

Long-acting injections

These injections take effect after 2 hours and last around 24 hours. Types of long-acting injections include:

Premixed injections

This type of medication consists of a combination of the above types of insulin. All take effect within 15–60 minutes and last 10–16 hours:

  • insulin lispro protamine and insulin lispro (Humalog Mix50/50 and Humalog Mix75/25)
  • insulin aspart protamine and insulin aspart (NovoLog Mix 50/50 and NovoLog Mix 70/30)
  • NPH insulin and regular insulin (Humulin 70/30 and Novolin 70/30)

Inhalable insulin

People can breathe in rapid-acting inhalable insulin, which takes effect within 12–15 minutes and lasts 2.5–3 hours. Currently, insulin human powder (Afrezza) is available.

Other drugs for type 1 diabetes

Some non-insulin injectable drugs are also common in the treatment of type 1 diabetes.

Amylin analogs, such as pramlintide (Symlin), mimic amylin hormones, which play a role in glucose regulation.

Glucagon medications can reverse blood sugar levels when they fall too low as a result of insulin treatment.

Insulin can also help manage high blood glucose levels in type 2 diabetes, but doctors typically prescribe it only if other treatments do not have the desired effect.

Pregnant people with type 2 diabetes may use insulin to reduce the effects of the condition on the fetus.

For people with high blood glucose levels, in addition to recommending lifestyle measures, doctors can prescribe non-insulin drugs to lower blood glucose. These drugs are listed below.

Many of the drugs have a combination of effects. If a person needs two or more treatments to manage glucose levels, insulin treatment may be necessary.


Biguanides boost the effect of insulin and are the most common medication for type 2 diabetes. They reduce the amount of glucose the liver releases into the blood, increase the uptake of blood glucose into the cells, and decrease glucose absorption in the intestines.

Metformin is the only licensed biguanide in the United States in the form of Glucophage, Glucophage XR, Glumetza, Riomet, and Fortamet.

Learn more about metformin here.


These drugs improve insulin secretion from the pancreas into the blood and reduce glucose output from the liver. People use the following newer medications most often, as they are less likely to cause adverse effects than older medications:

The older, less common sulfonylureas are:

  • chlorpropamide (Diabinese)
  • tolazamide (Tolinase)
  • tolbutamide (Orinase)

Today, doctors prescribe sulfonylureas less often than they did in the past. This is because these medications can cause very low blood sugar, which leads to other health problems.


Meglitinides enhance insulin secretion. These might also improve the effectiveness of the body in releasing insulin during meals. Meglitinides include nateglinide (Starlix) and repaglinide (Prandin).


Thiazolidinediones reduce the resistance of tissues to the effects of insulin. These medications have associations with serious side effects, so a doctor should monitor a person for potential safety issues when they are taking these. People with heart failure should not use these medications.

Alpha-glucosidase inhibitors

Alpha-glucosidase inhibitors cause the body to digest and absorb carbohydrates more slowly. This lowers blood glucose levels after meals. Alpha-glucosidase inhibitors include acarbose (Precose) and miglitol (Glyset).

Dipeptidyl peptidase (DPP-4) inhibitors

DPP-4 inhibitors slow the rate at which the stomach contents empty and slow glucose absorption.

DPP-4 inhibitors also block DPP-4 enzyme, a process that stimulates the pancreas to produce more insulin and the liver to produce less glucose.

Some examples of DPP-4 inhibitors are:

Sodium-glucose cotransporter 2 (SGLT2) inhibitors

SGLT2 inhibitors cause the body to expel more glucose into the urine from the bloodstream. They might also lead to a modest amount of weight loss, which can be beneficial in type 2 diabetes.

Some examples of SGLT2 inhibitors are:

Incretin mimetics

Incretin mimetics are drugs that mimic the hormone incretin, which stimulates insulin release after meals. These include:

Oral combination drugs

Several products are available that combine some of the drugs mentioned above. These include:

  • alogliptin and metformin (Kazano)
  • alogliptin and pioglitazone (Oseni)
  • glipizide and metformin (Metaglip)
  • glyburide and metformin (Glucovance)
  • linagliptin and metformin (Jentadueto)
  • repaglinide and metformin (PrandiMet)
  • pioglitazone and glimepiride (Duetact)
  • pioglitazone and metformin (Actoplus MET)
  • saxagliptin and metformin (Kombiglyze XR)
  • sitagliptin and metformin (Janumet and Janumet XR)

The FDA has approved one ergot alkaloid, bromocriptine (Cycloset), for type 2 diabetes. However, doctors do not often recommend or prescribe this medication.

People use bile acid sequestrants to manage cholesterol levels, but this type of medication can also help keep blood sugar levels steady. Only colesevelam (Welchol) has approval for type 2 diabetes.

Managing complications

Some drugs may help prevent the complications of diabetes.

High blood pressure

To treat high blood pressure, a doctor may prescribe ACE inhibitors or angiotensin II receptor blockers. These drugs also help prevent or manage kidney-related complications of diabetes.

Learn more about drugs for high blood pressure here.

Cardiovascular complications

People can manage the cardiovascular risks of diabetes, such as heart disease and stroke, by taking statins to lower cholesterol levels and a low dose aspirin once per day if their doctor recommends it.

Learn more about lowering cholesterol here.

Weight management

Reaching and maintaining a moderate weight is a key part of diabetes management and prevention for many people, particularly in relation to type 2 diabetes. If lifestyle measures have not helped with this, a doctor might suggest medicines such as the following:

  • Lorcaserin (Belviq): This drug increases the feeling of fullness after eating and helps address the obesity that often accompanies diabetes.
  • Orlistat (Alli and Xenical): Orlistat reduces the amount of fat the body absorbs from food and supports weight loss.
  • Phentermine and topiramate (Qsymia): This combination drug suppresses appetite and is an approved treatment for obesity.
  • Lemaglutide (Wegovy): This medication mimics the activity of the GLP-1 hormone and can reduce a person’s appetite.

Current guidelines urge doctors to look at each person’s situation and suggest the best approach for the individual.

For people with both type 2 diabetes and atherosclerotic cardiovascular disease (CVD), 2018 guidelines recommend including SGLT2 inhibitors and glucagon-like peptide 1 receptor agonists (GLP1-RA) as part of diabetes treatment.

These two medications are also suitable for people with type 2 diabetes and chronic kidney disease.

For those with type 2 diabetes, atherosclerotic CVD and heart failure, or a high risk of heart failure, doctors should prescribe SGLT2 inhibitors.

There is evidence that these can prevent chronic kidney disease, CVD, or both from worsening.

Learn more about CVD here.

People with type 1 diabetes cannot take insulin orally because the stomach breaks down the hormone. This means that injections and insulin pumps are the main ways for insulin to reach the bloodstream.

Diabetes researchers have explored other ways, but these new methods require more study before wider use. Nasal sprays and patches on the skin are possible future delivery methods for insulin.

An artificial pancreas is also an option. This device uses sensors to monitor blood sugar levels electronically and release the necessary amount of insulin.

Surgeons could also transplant insulin-producing pancreatic cells from donors. Some people already benefit from the early progress of research into islet cell transplants.

Personalized medication is a promising possibility for treating all types of diabetes. Developments in genetics and big data may lead to better grouping of the diseases and more targeted treatment.

Type 1 and type 2 diabetes affect the body differently and require different medications.

A person with type 1 diabetes will require injectable, intravenous, or inhalable insulin.

People with type 2 diabetes will typically require metformin and other medications that increase insulin secretion and reduce glucose levels.

In addition to treating the direct effects of diabetes, doctors may recommend medications to treat other conditions associated with diabetes. These may include weight loss medications to help people reach a moderate weight and ACE inhibitors to lower blood pressure.