Can Antibiotics Raise Blood Sugar? 7 Drugs You Should Know

Many factors can influence blood sugar. You’ve probably thought about how foods or physical activity can impact your blood sugar, but did you know that some medications can affect your blood sugar, too? While some drugs may lower blood sugar levels, many have the opposite effect. Taking these medications can make it more challenging to manage your blood sugar and can potentially cause or worsen diabetes. Talking to a healthcare provider about which medications are right for you is important.

Keep reading to learn about different medications that can affect your blood sugar, what they are used for, and strategies for managing blood sugar if you’re taking one of these medications.

Fluoroquinolones

Fluoroquinolones such as ciprofloxacin (Cipro), norfloxacin (Noroxin), and levofloxacin (Levaquin), are a class of antibiotics used to treat bacterial infections like urinary tract infections, bladder infections, and bronchitis. Like most antibiotics, they can cause some side effects, including nausea, vomiting, and diarrhea. Taking probiotic supplements may help with these effects by supporting gut health. Apart from gastrointestinal (GI) symptoms, one of the more serious side effects is changes in blood sugar level, called dysglycemia.

A study of more than 6,000 people taking fluoroquinolones found that more than one-third had hyperglycemia (high blood sugar), and another third had hypoglycemia (low blood sugar).¹ While people with diabetes are not at higher risk of these changes in blood sugar, they should be careful because low blood sugar can lead to serious problems like coma. It’s important to check your blood sugar often when you are on these medications to avoid sudden spikes or drops. This is especially true in people already taking medications to lower blood sugar since low blood sugar can be very dangerous. Some antibiotics, such as cephalosporins, have a milder effect on blood sugar than others, so your doctor may be able to prescribe an alternative treatment.

Antibiotics are usually only taken for a short period, and their effects on blood sugar may stop once you finish taking them. However, some research suggests that using antibiotics might be linked to the development of diabetes,² though it’s not clear why. 

Antibiotics might influence the risk of type 2 diabetes by changing the gut microbiota, which is known to play a role in metabolism and could potentially affect glucose regulation and insulin sensitivity. People who are likely to get diabetes may also be more likely to get infections and need antibiotics to treat them. 

If you’re checking your blood glucose levels, watch for any usual readings while on antibiotics, and talk to your healthcare provider about any needed changes in medication or insulin dosing.

Corticosteroids

Corticosteroids, known as steroids, such as prednisone, are drugs used to treat a wide range of inflammatory or autoimmune conditions, ranging from asthma to Crohn’s disease to rheumatoid arthritis. These drugs may be taken orally (by mouth), topically (on the skin), by inhaler, or by injection.

When you take steroids by mouth, they may raise blood sugar. Normally, when you eat carbohydrates, your body turns them into sugar and releases insulin. Insulin acts as the key that unlocks your body’s cells, allowing sugars in (and taking them out of the blood). Steroids interfere with this process by blocking insulin production. With less insulin in the body, sugar stays in your blood for longer, raising blood glucose levels. Even steroid injections can cause high blood sugar.³ One study found that corticosteroid use increased average blood sugar by as much as 27.4 mg/dL in people in the hospital.⁴

If you already have diabetes, you may need to adjust your insulin dose or even begin taking insulin shots when you take steroids. Your doctor may also ask you to check your blood sugar more often. Even if you do not have diabetes, steroids can cause a condition called “steroid-induced diabetes,” but this usually goes away once you stop taking the medication.

Statins

Heart disease is the leading cause of death in the United States, and high cholesterol is a main risk factor for it. Your body needs some cholesterol to work properly and can even make some on its own. But when there is too much cholesterol, it can build up in your arteries and form plaque. Statins are medications that help lower cholesterol by blocking an enzyme in the liver called HMG-CoA reductase, which is needed to make cholesterol. Doctors often prescribe statins to people with high cholesterol to reduce their risk of heart disease. Some common types of statins include atorvastatin, simvastatin, and lovastatin.

Type 2 diabetes is a known risk factor for heart disease. People with diabetes may be more than twice as likely to develop heart disease! Statins are often prescribed to people with diabetes to reduce this risk. However, statins can also affect how your body uses glucose (sugar). They can reduce the amount of insulin produced by the pancreas and make your body less responsive to insulin.⁵ The result: increased blood sugar.

Importantly, not all statins affect blood sugar in the same way.⁶ Research has found that people with prediabetes and diabetes are more likely to experience significant increases in blood sugar while taking statins compared to those without these conditions. While the American Heart Association and American College of Cardiology acknowledge this concern, they also agree that the benefits of statins generally outweigh the risks.⁷ It is still important to regularly check your blood sugar while on statins, especially since they are usually taken long-term. Talk to your doctor about other medications that can be used to lower cholesterol.

Beta-Blockers

Beta-adrenergic blockers, also known as beta-blockers, are commonly used to treat heart-related conditions like high blood pressure (hypertension) and heart attacks. Medications like metoprolol or propranolol are beta-blockers that help lower blood pressure in several ways. First, they work by blocking the release of hormones like adrenaline that can speed up the heart rate. This is similar to slowing the flow of water through a hose - the slower the flow, the lower the pressure. Beta-blockers also prevent the kidneys from releasing the hormone called angiotensin II, which normally causes blood vessels to tighten. By blocking this hormone, beta-blockers help relax and widen the blood vessels. This is like switching from a narrow hose to a wider one. The wider hose allows water (or, in this case, blood) to flow more easily, which lowers pressure in the blood vessels.

While beta-blockers are helpful for many, they can make it harder to notice if your blood sugar is low. For example, low blood sugar often causes a fast heartbeat. But beta blockers slow the heartbeat. You may not feel it when your blood sugar gets too low. If you have diabetes, you may need to check your blood sugar more often and watch out for other symptoms of low blood sugar, like feeling dizzy or confused.

Some studies also show that beta blockers can increase the risk of getting diabetes in people who don’t already have it. A study of almost 100,000 people found that beta blockers increased the risk of developing diabetes by 22%.⁸ Certain types of beta-blockers may have less effect on blood sugar and might be a better choice for people with diabetes.⁹ Your doctor might suggest a different type of beta blocker for you.

Psychiatric Medications

Antipsychotic drugs like chlorpromazine (Thorazine) and aripiprazole (Abilify) are commonly used to treat mental health conditions such as bipolar disorder and schizophrenia. People taking these medications are about 2-3 times more likely to have diabetes than the general population, but it is hard to determine whether antipsychotic drugs themselves cause diabetes or whether diabetes risk is higher because antipsychotics can cause weight gain that can lead to insulin resistance.¹⁰

If you’re taking antipsychotics, it’s important to keep track of your blood sugar. Making healthy lifestyle changes, like choosing foods with lower glycemic index and exercising more, can help lower your risk of diabetes. But for people with schizophrenia, these changes might not work as well.¹¹ Working with a mental health professional, dietitian, and endocrinologist is important to help you control your blood sugar.

Decongestants

Decongestants are commonly available over-the-counter in various forms, including nasal sprays, tablets, and liquids. You have probably reached for a decongestant, like pseudoephedrine or phenylephrine, to clear up a stuffy nose from a cold or allergies. When you get the flu, your immune system sends extra blood to your nose to fight the virus. This causes your blood vessels to swell, causing inflammation, congestion, and the production of mucus to flush out the virus. Decongestants work by narrowing the blood vessels in your nose to clear the airways and reduce swelling. Decongestants help you breathe better but also trigger your body’s “fight or flight” response,

This “fight or flight” response increases heart rate, blood pressure, and blood glucose levels to help you respond to perceived threats. This may have been helpful for a caveman running from a woolly mammoth, but it is less helpful now if you are sick. An unwanted spike in glucose may make it harder to control your blood sugar levels. If you have high blood pressure or a heart condition, this “fight or flight” response may also make it difficult to manage these other conditions.

Talk to your doctor about other ways to treat your cold or allergies, like saline or steroid nasal sprays.

Birth Control Pills

There are many reasons to take birth control pills, such as reducing unwanted pregnancies, treating health conditions like endometriosis or polycystic ovary syndrome, reducing menstrual cramps, and convenience. There are two main types: pills with both estrogen and progesterone (combined pills) and pills with only progesterone (known as the mini-pill).

Although high levels of female sex hormones may cause insulin resistance, it’s not clear how birth control pills affect blood sugar. The effects seem to depend on the type of birth control that you use. Some studies have found that the pills may raise insulin and blood glucose levels, while others show an effect only from the depo-provera shot but not from pills.^12,13 If you’re taking birth control pills and notice any changes in your blood sugar, talk to your doctor about other options, such as condoms, patches, and IUDs.

If birth control pills can increase blood sugar and insulin, can they cause diabetes? Some forms of birth control may increase the risk of type 2 diabetes in certain groups of people. For example, one study of Latina women who had recently gotten gestational diabetes during pregnancy found that the mini pill increased the risk of diabetes.¹⁴ Despite this, most research does not find this link and birth control pills are considered safe for long-term use.

The Bottom Line

Whether you have diabetes or are trying to prevent it, it’s important to be aware of how some medications can impact blood sugar. Work with your healthcare team to find the right medications and treatments for you and consider other lifestyle changes like eating healthier, exercising, and managing stress, to keep your blood sugar in check.

Learn More About How to Improve Blood Sugar Health With Signos’ Expert Advice

Blood sugar health seriously affects how you feel and how well your body functions. That’s why choosing the right medication and making healthy choices to manage your blood sugar is important. Understanding the connections between medications, lifestyle choices, and blood sugar can give you the tools that you need to stay healthy.

Signos CGM empowers you to improve your health by tracking your diet, exercise, sleep habits, and blood sugar. Knowledge is power, and a CGM can give you specific information about how your habits affect your health. 

Signos has a team of health experts who compile evidence-based nutrition information to help you improve your health and wellness. Check out the resources here. Take a quick quiz to determine if Signos is a good fit for you.