Diabetes medications and side effects

Key takeaways:

• Different classes of diabetes medications cause varied side effects. Common side effects people on diabetes medications may experience include nausea, weight gain, fatigue, headache, and constipation. 
• Conditions such as heart failure can impact the severity of side effects and the effectiveness of diabetes medications. 
• While diabetes medications can cause side effects, their benefits for managing blood glucose levels often outweigh the risks, and many people do not experience any side effects at all, while some of those who do only experience mild side effects that gradually resolve. 

Diabetes, also called diabetes mellitus, is a disease that occurs when there is too much glucose in the blood. If left unchecked, diabetes can cause serious damage to the body. 

There are three types of glucose-related diabetes: 

• Type 1 diabetes: In this type of diabetes, the immune system attacks the beta cells in the pancreas that produce insulin (a hormone that regulates blood glucose), leading to little or no insulin production. 
• Type 2 diabetes: People with type 2 diabetes either don’t produce enough insulin or their cells aren’t sensitive to the hormone (insulin resistance). In some cases, it’s both.
• Gestational diabetes: This type of diabetes can develop during pregnancy. Although it usually resolves after childbirth, it increases the risk of type 2 diabetes in the future. 

Diabetes doesn’t have a cure. Therefore, managing the condition with medications is key to lowering the risk of severe complications. However, these medications aren’t without side effects. 

This article highlights common diabetes medications and their potential side effects. It also emphasizes the importance of proper blood glucose monitoring and management for people living with diabetes.  

1. Insulin

Insulin medication mimics the one produced by the body. It facilitates glucose uptake by the cells as an energy source. Any excess glucose is converted to glycogen and stored in the liver.

Insulin is administered via subcutaneous (under the skin) injection. There are different types of insulin, as shown in the table below:

Side effects of insulin injection

People who take insulin injections can experience:

• Weight gain 
• Pain at the injection site
• Hypoglycemia (low blood sugar)
• Lipodystrophy (Fat loss that causes changes in skin texture) 

2. Biguanides

Metformin is the most common biguanide and the only one approved by the United States Food and Drug Administration (FDA) for managing type 2 diabetes. 

Biguanides prevent the liver from producing glucose and also increase the sensitivity of cells to glucose. Additionally, they increase the amount of glucose the kidneys excrete while reducing the amount of glucose the body absorbs from food.

Side effects of biguanides

Biguanides (metformin) can cause:

• Fatigue
• Nausea
• Indigestion
• Muscle pain
• Diarrhea and constipation
• Headache
• Constipation

3. Thiazolidinediones

This class of drug activates peroxisome proliferator-activated receptors gamma (PPAR gamma). When activated, these receptors help to improve insulin sensitivity in patients with type 2 diabetes. 

Pioglitazone and rosiglitazone are common examples of thiazolidinediones. 

Side effects of thiazolidinediones

Adverse effects associated with thiazolidinediones include: 

• Weight gain
• Blurry vision
• Fluid retention
• Increased ovulation rate 
• Increased risk of fractures

4. Dopamine-2 agonists

Bromocriptine is a dopamine D2 agonist initially used to treat pituitary tumors. However, in 2009, the Food and Drug Administration (FDA) approved it as a treatment drug for type 2 diabetes. 

This drug is believed to act on the hypothalamus to reduce glucose production in the liver and improve insulin sensitivity. 

Side effects of dopamine-2 agonists

Bromocriptine can cause side effects such as:

• Heartburn
• Headache
• Drowsiness
• Constipation
• Stomach upset
• Loss of appetite 

5. DPP-4 inhibitors

DPP-4 inhibitors block the action of Dipeptidyl peptidase-4 enzyme. DPP-4 enzyme inactivates incretin, a hormone that helps the body produce more insulin after a meal. 

In addition to helping the body produce insulin, incretin also reduces the amount of glucose the liver releases and slows down gastric emptying, which helps you stay fuller for longer.

Side effects of DPP-4 inhibitors

Common adverse reactions associated with the use of DPP-4 inhibitors are:

• Headache 
• Urinary tract infection 
• Upper respiratory tract infection 

6. Alpha-glucosidase inhibitors

This class includes drugs such as acarbose and miglitol. They prevent the absorption of simple carbohydrates from starchy foods like bread, rice, and potatoes.

Alpha-glucosidase inhibitors are taken three times a day before each meal to reduce the spike in blood glucose levels after meals.  

Side effects of alpha-glucosidase inhibitors

This drug can cause side effects such as:

• Diarrhea 
• Stomach pain 
• Flatulence (gas) 

7. Sulfonylureas

Sulfonylureas like glipizide and glimepiride stimulate the pancreatic beta cells to produce insulin. This action is independent of the amount of glucose in the blood. 

Due to how they work, sulfonylureas are only beneficial in patients with functional beta cells in their pancreas. 

Side effects of sulfonylureas

Sulfonylureas can cause mild to serious side effects such as:

• Hunger
• Diarrhea
• Dizziness
• Headache 
• Increased heart rate 
• Hypoglycemia (low blood glucose)

8. SGLT2 inhibitors

Sodium-glucose cotransporter 2 (SGLT2) inhibitors such as empagliflozin and dapagliflozin prevent glucose reabsorption in the kidneys. The excess glucose is excreted through the urine. 

SGLT2 inhibitors are taken in the morning, before the first meal of the day. They are usually used when other antidiabetic medications fail to achieve satisfactory blood glucose control. 

Side effects of SGLT2 inhibitors

Using SGLT2 inhibitors can cause:

• Nausea 
• Constipation
• Frequent urination 
• Urinary tract infections 

Side effects of long-term use of diabetes medications

Diabetes medications can cause negative side effects when used for the long term, which is usually the case in the management of diabetes. 

The most common ones are: 

• Cardiovascular risks: Prolonged use of thiazolidinediones has been linked with a significantly higher risk of heart failure.
• Bone fractures: Thiazolidinediones can cause bone loss over time and increase the risk of fractures.
• Vitamin B12 deficiency: Long-term use of metformin has been associated with vitamin B12 deficiency and anemia.

Effects of not taking your diabetes medication

While diabetes medications can cause potential side effects for some people, not taking your diabetes medications or not taking them as prescribed (when your blood sugar levels are high) has both long- and short-term consequences. 

In the short term, you may experience symptoms of hyperglycemia (high blood glucose), like:

• Fatigue 
• Headaches
• Blurred vision
• Increased thirst 
• Frequent urination 

Hyperglycemia can also give rise to diabetes-related ketoacidosis (DKA). This condition occurs when the body is unable to utilize glucose for energy due to low insulin levels and starts breaking down fat to produce acids known as ketones. 

When ketones build up in the bloodstream due to rapid fat breakdown, they can cause serious symptoms such as: 

• Nausea
• Vomiting
• Confusion 
• Abdominal pain 
• Difficulty breathing 

If left unchecked, hyperglycemia can damage your organs and nerves and cause diabetes-related complications.

Health conditions that can affect how your diabetes medications work

Certain health conditions can affect how diabetes medications work, heightening or reducing their effects. 

Examples of these conditions are: 

• Kidney disease: Chronic kidney disease can impair kidney function. This affects the kidney’s ability to eliminate drugs, which build up in the blood and increase the risk of side effects. 
• Liver disease: Drugs that are metabolized (broken down so they can be excreted) by the liver can accumulate in the body when it is diseased and not functioning normally.
• Congestive heart failure: The heart’s inability to pump blood effectively can affect the absorption and clearance of drugs from the body, increasing the risk of toxicity.
• Gastrointestinal disease: Diseases that affect the gut can alter the amount and rate of drug absorption. This increases the risk of adverse side effects or renders the dose ineffective.

How to manage hypoglycemia at home

Hypoglycemia is a serious side effect associated with medications like insulin and sulfonylureas. It is defined as a blood glucose reading below 70 milligrams per deciliter (mg/dL).

In episodes of hypoglycemia, your blood sugar can drop significantly and rapidly and can be fatal if not caught on time. 

Symptoms of hypoglycemia to look out for are:

• Hunger
• Tiredness
• Confusion
• Headache
• Shaking or jitteriness
• Fast or irregular heartbeat

In severe cases, you may lose consciousness or have a seizure. 

Check your blood glucose levels regularly. If it's low or if you notice symptoms of low blood sugar, follow these steps:

1. Eat or drink 15 to 20 grams of glucose or carbohydrates immediately. Glucose tablets, fruit juice, honey, and soda are great options for raising blood glucose. 
2. Wait for 15 minutes and check your blood glucose again. If it is still low, eat or drink another 15 to 20 grams of glucose or carbohydrates. 

3. Repeat the process until your blood glucose is back to its normal range. 

If there’s no improvement after consuming several grams of glucose or carbohydrates, you can use a glucagon kit if you have one, or call emergency services. 

Seeking medical attention for diabetes medication side effects

Diabetes medications cause unpleasant side effects; this is to be expected in most cases. However, if the side effects are severe enough to interfere with your daily routine, contact your doctor. 

Your doctor is in the best position to conduct a proper evaluation and prescribe an alternative medication if necessary. 

They may also adjust dosing if the heightened side effects you’re experiencing are a result of an underlying health condition such as heart failure or kidney disease.