Metoprolol Side Effects

I have recently had my metoprolol dose doubled as I was having breakthrough tachycardia. My blood sugars are now high and I have been using a temp basal to try to manage through for now until I can sort this out. However, even worse is my resistance with my food boluses. I already eat low carb but I am having to bolus like I’m eating the standard american diet full of carbs. I might as well be bolusing with water. I hadn’t noticed this on my old dose but the more I think about it I wonder if I have been having some insulin resistance prior to dose change just not enough for me to really pick up. Anybody with similar problems with beta blockers and what would be the next choice of meds? I like to be informed before I talk to my cardiologist, we often don’t see eye to eye on things.

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How do you deliver your insulin, injections or pump? How long have you had diabetes? Do you rotate injection or infusion sites to mitigate scarring? Are any of your usual sites sore to the touch? Are there any other possible explanations, such as menopause? Has your weight been stable over the last several years or has it been slowly climbing, like 2 pounds/year? What has been your total daily insulin dose (bolus + basal) trend over the last few years?

I checked out one website regarding beta-blocker side effects but didn’t see any mention of increased insulin resistance. I know these side-effect lists are not comprehensive and your question is a reasonable one. Do you regularly drink coffee and/or a alcohol? The website I read stated that caffeine and alcohol can change how beta blockers work in your body. It also stated that older people (60+) experience more unwanted side effects.

Looking for clues to your question taught me something. I take a beta-blocker, too, and this website cautioned that beta-blockers can trigger a severe asthma attack. I don’t have a history of asthma but I ended up in the emergency room recently complaining of shortness of breath.

Good luck with discovering the source of sudden increased insulin resistance. I also endure substantial conflict with my cardiologist, interesting that your profession (I conclude you’re a nurse from your screen name) does not inoculate you from that patient hazard.

Final thought, you might ask the doctor to prescribe a different beta-blocker to help you troubleshoot this significant and sudden insulin resistance scenario. Also, talk to a pharmacist about this; s/he may be better informed about your question.

Thanks for your thoughtful response. I have had type 1 for 37 years, I pump and CGM. My diabetes management consists of a regular day never being the same so I am constantly ruling out things like site problem, pump malfunction, menopause, etc. The onset was so acute and has continued that I’m pretty sure I’ve ruled out all of those other things at this point. On my own, I’ve just restarted my old dose and will continue to monitor and see.
A couple of other providers have commented to me about the high dosing, and I have had some low blood pressures and fatigue as well with this new dosing. I was at my retina appointment yesterday getting my angio and they also commented that my bp must be pretty low because it took so long for the dye to get to my eyes.
Interestingly enough, this morning when I posted this I noticed, but had forgotten that last year when I started the metoprolol I was having some unexpected hypoglycemia with it. But it must have resolved, I really can’t remember.
Yes, my cardiologist. He is old school and Has no regard for the fact that I am a nurse, I can read a study and understand it or that I am a patient and have a right to participate in my own care despite his views on low carb diet, statins, etc.


Due to the brief reading I did prompted by your post, I called a pharmacist this morning. She confirmed that the propranolol I’m taking could be the cause of the shortness of breath I’ve been experiencing. Both of my doctors, primary and endo, missed making this observation. I hope this is true in my case as it’ll be much easier to fix than a pulmonary deficit of some sort.

Good luck with discovering what’s going on in your case. Please update if you find out what’s happening.

Yes, that is my understanding of metroprolol’s effect on blood sugar.

Your first post however noted a connection to hyperglycemia, which is interesting. I can’t find any info about metoprolol and elevated sugar.

In terms of respiratory effects, my drug book indicates that beta2 receptors (in the lungs, in this case) are blocked only when metoprolol is taken at high doses. However, side effects (really “adverse” is more like it) under the “resp” category are bronchospams, dyspnea and wheezing. In other words, in one place they say respiratory side effects occur only at high doses, in another place that distinction is not made.

And again, in terms of blood sugar and metoprolol, what I learned is that beta blockers can mask hypoglycemia. My drug book says that together with insulin, metoprolol can lead to actual hypoglycemia as well. So I’m a bit lost on the connection between hyperglycemia and metoprolol.

I have to say I have used a high dose of metoprolol for sometime with not had noticeable impact on my blood sugar. Maybe I have used it so long, I have forgotten the impact. I hope you are able to find a solution to the issue. The impact sounds awful.

What I’m finding is that hyperglycemia or high blood sugars are not listed anywhere in the standard side effects or anywhere really. But when you start looking at studies they all same glycemic control is worsened on Metoprolol compared to other beta blocker like Cardivelol or a calcium channel blocker. I found these which were helpful, but I am having a hard time understanding “insulin stimulating endothelial function”.

From that study the “insulin stimulating endothelial function was deteriorated after treatment with metoprolol…” The technicalities of the insulin stimulated endothelial function is a little over my head but why wouldn’t it be the same for me?

Also found this:
Again, doesn’t directly say causes high blood sugars but compares different med approaches for BP and notes the worsening metabolic or glycemic effect of metoprolol.
I went back to my lower dose yesterday and I was able to stay in range with the exception of one slight excursion and at target all night. First time in 10 days, coincidence?

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That is fantastic! Congratulations on your great research!

I do not have the brain power either to understand very well or explain how endothelial function relates to insulin resistance, but someone like Irish researcher/engineer Ivor Cummins might.

He thinks that “most heart disease is diabetic dysfunction or insulin resistance.” The pathways are insulin resistance and hyperinsulinemia. This next part is italicized because I have it saved, but don’t know if it’s a direct quotation or not. Insulin resistance promotes raised inflammatory markers, TNF alpha is raised, fat cells swell, insulin is raised. Insulin signalling will not work so well inside fat cells, lowering adipolectin. High insulin incorporates lipids into vascular wall/endothelium. High glucose spikes will glycate and damage components in plasma and LDLs and blood cells. Hyperinsulinemia and hyperglycemia disturb the whole milieu in the body.

He’s talking about heart disease, but also about insulin’s impact on the endothelium (which leads to heart disease). Perhaps you’ve heard of him. Just a random google yields this site, which may be of help.

I will not even attempt to understand the difference between metoprolol and carvedilol in terms of endothelial function.

I am a big fan of Ivor! Been following him and his research since I started low carb. Ivor’s really pushing the CAC as a predictor for heart disease and the research is there and I actually found a recommendation from the ADA (not that I routinely take their advice) that CAC testing in menopausal women with type 1 diabetes may help predict an increase risk for that population. I brought that info to my cardiologist and he completely poo-pooed the evidence I presented to him.
Dave Feldman is another guy, an engineer, N=1, studying himself and lipidology. Really interesting stuff.


Yes, I have heard Dave Feldman too. In particular he was on Peter Attia’s podcast. PA was a total #&@& to him and listening to that podcast was tough. Normally I like Attia a lot.

At any rate, now you know (and so do we!): there is a meaningful difference between those two beta blockers.

Have you considered Flecainide?

I’ve never heard of that one so I looked it up. Huge list of side effects and says usually reserved for life threatening ventricular arrhythmia. I will pass on that one if my cardiologist suggests.

I was on propranolol after I was diagnosed with Graves’ disease and I definitely noticed an impact on my asthma. I’ve been on bisoprolol for years and that’s had no impact on asthma, the only side-effect I’ve had with it is fatigue. My understanding is that they are from two different classes of beta blockers, one that affects the entire body and one that mostly just affects the heart.

As to blood sugar, I’ve never noticed any impact on my blood sugar. But my blood sugar is volatile enough that it can be hard to notice individual variables like that.

Thanks for this feedback, Jen. I’ve now learned from participating in this thread that beta-blockers can be broken down into three subclasses: nonselective, cardioselective, and third generation.

Propranolol is nonselective and affects both heart and lung tissue, whereas the bisoprolol is cardioselective and only affects the heart.

I will see a new primary care provider next week with this being the main reason for the visit. I will suggest to her that we try a cardioselective beta-blocker to replace the nonselective propranolol that I’m currently using.

By the way, I found this Harvard Medical School short article entitled, Beta blockers: Cardiac jacks of all trades, a concise summary of beta blockers.

Is the fatigue at least manageable on the bisoprolol? With 200mg metoprolol succinate I had such bad fatigue that when I was at work when I went to lunch I had to go to sleep instead of eat!

Yes, it is manageable. My cardiologist suggested taking it in the evening to help minimize that side effect. I notice it mostly because I’ve tried several times to get off beta blockers (they can block epinephrine, which is dangerous for people who carry EpiPens, as I do), and I notice it mostly when trying to exercise. I have much more energy without the beta blocker when exercising, but so far I’ve always developed significant tachycardia and related symptoms and had to resume taking it. I have managed to get to a very low daily dose (just 1.25 mg per day) that still lowers my heart rate significantly, so I’m hoping that my next attempt to discontinue may be more successful.

This is why I’m surprised someone would prescribe propranolol for cardiac/blood pressure purposes these days. I see it almost exclusively used as a psychiatric med, where the nonselective nature is ideal (also more nervous system activity)—it’s commonly used for performance anxiety and other anxiety disorders. It works fabulously for things like fear of public speaking. Worsening asthma is a well known side-effect, so I’m also surprised your docs missed that, but it exemplifies why I’ve learned to research every med I take myself, because often doctors miss stuff about pharmacology.

Doctors are under many pressures in their work. I understand that limited resources, especially time, adversely impact their ability to do their job competently.

What I don’t get is their seeming incompetence with something as important as pharmacology. Propranolol was prescribed initially to me about eight years ago by an endocrinologist to treat an elevated heart rate. It worked as intended and I didn’t experience any side effects until recently.

Since then I’ve visited a series of doctors including two more endocrinologists, one physician assistant, two primary care docs, and two or three doctors who treated me in the emergency room for shortness of breath. None of them raised the issue of propranolol being connected to asthma and a possible explanation for the symptoms I presented with.

At every appointment they always spent time going over my list of meds but apparently never with a critical eye toward side effects or adverse drug interactions! They are in the drug prescription business and should possess a competent working knowledge of pharmacology. If they’re unsure, they should be able to consult with a pharmacist.

I am losing respect for the basic skills that I think doctors possess. They are not simply fallible humans but for a variety of reasons, incompetent at their work.

I try to be an informed patient but I’m tired of having to persuade doctors to make good choices for me. They are so balled-up in their legal fears and hiding behind their standards of practice that they lose sight of simple things like, “first, do no harm!”

I’m losing my sympathy for the modern doctor’s plight and am beginning to think that I am essentially in the enterprise of my health on my own. When I bring ideas to improve my health to the doctors’ attention, I often wonder if they’ve even heard me. They’re quick to dismiss my ideas as unworthy of their time since they’re not covered by their immediate knowledge base.

I see a new primary care doctor (actually a nurse practitioner) tomorrow to get a replacement Rx for the propranolol. This will be an immediate test of the competency of this practitioner. I hope she surprises me, understands my issue, and moves quickly to fix it.


Yeah that’s really problematic. It should be an obvious flag. I’m still also surprised it was prescribed in the first place for tachycardia, vs a cardioselective one.

For what it’s worth, I take atenolol (a cardioselective drug) for tachycardia and POTS, and it works very effectively for that. Good luck with finding one that works for you—at least with beta blockers, they work very quickly and leave the system quickly, so should be able to figure out soon.

Are you saying, since you have had shortness of breath, you’ve visited about 8 doctors and none of them thought to connect the propranolol to that? If that’s the case, that’s egregious enough for a write-up of some kind.

Apart from that sad state of affairs, I would be interested in knowing your thoughts on why you think that medication started causing problems, when it hadn’t before? Also, have you stopped the propranolol? If so, how’s it going?