Common Diabetes Medication Mistakes

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Common Diabetes Medication Mistakes

If you have diabetes, taking medication may be part of your daily routine. You might be taking one or more medications for managing your blood sugars; on top of that, perhaps you take medications for managing blood pressure or cholesterol. Taking your meds is one thing; taking them as prescribed is something else. For example, should you take them with food? Is there a better time of day to take them? Talking with your healthcare provider or pharmacist can make a big difference in how effectively your medications work to get your numbers at goal. Let’s take a look at some of the common “mishaps” that can occur. Remember to always check with your healthcare provider if you have questions about your medications or are unsure how or when to take them.

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Diabetes medications

Today, there are so many different classes of diabetes medications, ranging from insulin to non-insulin injectables to pills. Hopefully your healthcare provider or pharmacist gives you precise directions on when and how to take them, but unfortunately, that’s not always the case.

Mealtime (bolus) insulin

Humalog and Admelog (generic name insulin lispro), Novolog (insulin aspart) and Apidra (insulin glulisine)

In general, these insulins are meant to be taken about 15 minutes before the start of a meal.


Taking these insulins after you’ve started eating, after eating or at bedtime.


Lyumjev (insulin lispro-aabc) and Fiasp (insulin aspart injection) are ultra-rapid acting mealtime insulins that can be taken at the start of a meal or within 20 minutes after eating. Also, some people with gastroparesis may do better with taking mealtime insulin after eating a meal due to having a slower digestion time.

Intermediate-acting insulin

Humulin N, Novolin N (NPH)

This insulin is usually given as two injections daily to help manage blood sugars between meals. Unlike long-acting insulins such as Lantus, Basaglar and Toujeo (insulin glargine) or Levemir and Tresiba (insulin degludec), NPH has a definite “peak,” or time when it’s working its hardest to lower blood sugars. Timing, therefore, is important.


Taking NPH insulin at bedtime can significantly increase the risk of hypoglycemia (low blood glucose) between 2 a.m. and 5 a.m., when you are likely to be sleeping.

If you take NPH twice daily, the ideal times to take it are in the morning, 30 to 60 minutes before breakfast, and then 30 to 60 minutes before dinner.

GLP-1 receptor agonists

Byetta and Bydureon (exenatide), Victoza (liraglutide), Adlyxin (lixisenatide), Trulicity (dulaglutide), Ozempic and Rybelsus (semaglutide)

With the exception of Rybelsus, all of these medicines are injected. Some are given daily, others once weekly.


Taking Victoza, Adlyxin or Byetta at varying times of the day.

The short-acting GLP-1 agonist Adlyxin is meant to be taken once daily within the hour before the first meal of the day. Byetta is to be taken twice daily, within an hour before the meal. Victoza is taken daily at any time of the day, with or without meals. The long-acting GLP-1 medicines Ozempic, Rybelsus, Trulicity and Bydureon are taking once weekly (the same day each week) at any time of day, with or without meals.


Taking Rybelsus with food or more than 4 ounces of water.

Rybelsus, which is the only GLP-1 inhibitor that is taken in pill form, must be taken daily on an empty stomach when you first wake up. You should take this with just a sip of water (no more than 4 ounces) and then wait 30 minutes to eat, drink or take other oral medications.


Glimepiride, glyburide and glipizide

Sulfonylureas were the first oral medications used to help treat diabetes. They work to increase the amount of insulin produced by the beta cells in the pancreas.


Varying the times of your meals or skipping a meal altogether.

Because there is a risk of hypoglycemia with sulfonylureas, it’s important that you take them before or with your first meal of the day (glyburide may be given twice daily); it’s also important to stay with a regular meal schedule as much as possible.

SGLT2 inhibitors

Invokana (canagliflozin), Farxiga (dapagliflozin), Jardiance (empagliflozin), Steglatro (ertugliflozin)

SGLT2 inhibitors are a relatively new class of drug for type 2 diabetes. Sometimes called “gliflozins,” SGLT2 inhibitors work on the kidneys to prevent the reabsorption of glucose; this means that glucose is excreted in the urine, helping to lower blood glucose levels.


Not drinking enough fluids when taking an SGLT2 inhibitor.

Because these drugs cause you to urinate more, you might become dehydrated. Dehydration can make it more likely for your blood pressure to drop; this can lead to dizziness or fainting, especially when you stand up. Ask your healthcare provider how much fluid you should drink if you are taking an SGLT2 inhibitor.

Cholesterol-lowering medication

Statins: Zocor (simvastatin), Mevacor (lovastatin), Lipitor (atorvastatin), Pravachol (pravastatin), Crestor (rosuvastatin)

Statins are medicines that lower blood cholesterol levels by blocking an enzyme in the liver that is needed to make cholesterol. The American Diabetes Association recommends that most people with diabetes take a statin, depending on age and other risk factors.


Taking Zocor or Mevacor in the morning.

Zocor and Mevacor have shorter “half-lives” than Lipitor, Pravachol or Crestor. For this reason, it’s better to take these two statins in the evening, since studies show a greater reduction in LDL (“bad”) cholesterol compared to taking them in the morning.


Eating grapefruit or drinking grapefruit juice if you take Lipitor, Zocor or Mevachor.

Grapefruit contains a chemical that blocks the action of the enzyme CYP3A4, which prevents the statin from being broken down. The result is that there is too much statin in your body, and that can lead to problems such as myopathy, or muscle pain. If you take a statin other than Lipitor, Zocor or Mevachor, you can enjoy grapefruit!

Blood pressure medications

Common blood pressure medications prescribed to people with diabetes include ACE inhibitors, ARBs, calcium channel blockers and thiazide diuretics.


Using a potassium-based salt substitute (e.g. Morton Salt Substitute, My Salt Substitute) if you take an ACE inhibitor or an ARB.

ACE inhibitors, such as lisinopril, captopril and enalapril, and ARBs, such losartan, candesartan and valsartan, work to relax blood vessels, which, in turn lowers blood pressure. One of the side effects of these medications is higher potassium levels in the blood. It’s best to avoid using a salt substitute that contains potassium unless you have discussed this with your healthcare provider.


Eating grapefruit or drinking grapefruit juice if you take a calcium channel blocker.

Grapefruit and grapefruit juice can interact with some calcium channel blockers (verapamil, nifedipine, felodipine), causing a lower heart rate, headaches and dizziness.


Taking an NSAID (non-steroidal anti-inflammatory drug) such as ibuprofen, ketoprofen or naproxen sodium if you take a thiazide diuretic (hydrochlorothiazide, chlorothiazide, metolazone).

Thiazide diuretics (“water pills”) work to reduce water and sodium in the body, which helps to lower blood pressure. NSAIDs can reduce the diuretic effect of the medication. Your provider may suggest that you take acetaminophen or aspirin for pain relief, instead.

Always let your provider or pharmacist know if you have questions about how any of your medications work, as well as when to take them, and if you should take them with or without food. Sometimes, your provider may advise you to take a certain medication in a different way (such as after a meal rather than before a meal) or at a different time than what is typically prescribed. Don’t change how your provider has advised you to take your medication, and don’t stop taking a medication without talking with your provider first.

Want to learn more about the role of medicines in treating diabetes? Read “Making Your Diabetes Pills Work for You” and diabetes educator Amy Campbell’s eight-part series on diabetes drugs, covering metforminsulfonylureasmeglitinidesthiazolidinedionesDPP-4 inhibitorsSGLT2 inhibitorsalpha-glucosidase inhibitorsbile acid sequestrants and dopamine receptor agonistsnon-insulin injectable diabetes medications, and insulin.

Amy Campbell, MS, RD, LDN, CDCES

Amy Campbell, MS, RD, LDN, CDCES

Amy Campbell, MS, RD, LDN, CDCES on social media

A Registered Dietitian and Certified Diabetes Educator at Good Measures, LLC, where she is a CDE manager for a virtual diabetes program. Campbell is the author of Staying Healthy with Diabetes: Nutrition & Meal Planning, a co-author of 16 Myths of a Diabetic Diet, and has written for  publications including Diabetes Self-Management, Diabetes Spectrum, Clinical Diabetes, the Diabetes Research & Wellness Foundation’s newsletter,, and

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