Concerns With Metformin And Janumet Causing Muscle Soreness

Answer

Thanks for reaching out to us! I can certainly answer this question in the context of how the two drugs you mention in your question (metformin and Janumet) may be contributing to your muscle soreness.

However, I am not an expert on the Apple Watch or how that device calculates VO2 Max (a measure of the maximum amount of oxygen that an individual can utilize during intense or maximal exercise).

Based on documentation that I found from Apple, it appears the watch estimates an individual's V02 max using a combination of factors, including the individual's age, gender, respiration rate, and heart rate data. I don't know how accurate the calculation is when compared to when more specialized equipment is used (which typically involves an individual undergoing intense exercise with equipment that measures things like heart rate, oxygen uptake, and carbon dioxide production).

So, I'll focus on the drugs and side effects that relate to your question.

Janumet And Metformin Causing Muscle Soreness And Fatigue

In your question, you mention that you found your muscles get sore quickly after starting Janumet and metformin. The common thread here is the drug metformin since metformin is one component of Janumet (Janumet consists of Januvia [sitagliptan] and metformin).

I'm not sure if you were taking both at the same time, or were switched from one to the other, but it appears that metformin is a drug that is associated with your muscle problems.

Additionally, the fact that your symptoms resolved after stopping these drugs is definitely a strong indicator that they could have been at least partially responsible for the issues you were experiencing.

You Should Always Be On The Lookout For Muscle Pain With Metformin

Now, metformin is associated with causing myalgia (muscle pain) and soreness as it can increase lactic acid levels.  Per the prescribing information for the drug, this side effect occurs in 1-5% of individuals.

Additionally, while rare, metformin has been linked to causing lactic acidosis, generally in cases where too much metformin is taken for too long of a time. Lactic acidosis is a condition where there is an excess of lactic acid in the body and symptoms include abdominal pain, nausea, vomiting, rapid breathing, and muscle weakness. If left untreated, lactic acidosis can be serious and may lead to coma or death.

The prescribing information for metformin, and any drug that contains it, has a black box warning for lactic acidosis:

Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. The onset of metforminassociated lactic acidosis is often subtle, accompanied only by nonspecific symptoms such as malaise, myalgias, respiratory distress, somnolence, and abdominal pain.

The symptom of muscle soreness you are experiencing is certainly a fairly common and non-specific side effect that many drugs or other factors can cause. I mention it here because you have associated it with metformin and it's extremely important to be aware of.

Muscle soreness alone doesn't mean you are experiencing lactic acidosis, and you may just be one of the individuals that, unfortunately, are experiencing it as a general side effect of the drug and could be causing the athletic performance problems you discussed. It is important to let your doctor know about it if you haven't already done so so you can be appropriately evaluated and monitored.

Januvia And Pain

Januvia (sitagliptin) is less associated with muscle pain than metformin, but it has been reported.

More commonly though, DPP-4 inhibitors, the drug class to which Januvia belongs, is associated with arthralgia or joint pain. In fact, the FDA has released a safety statement regarding cases of joint pain in those taking the drug.

Other Drug Options

There are a number of different treatments available for those who have been diagnosed with type II diabetes, and the choice of therapy depends on many different factors.

It's difficult to give a precise recommendation since there are so many factors, but there are other drug classes available to you, such as:

• Insulin
• GLP-1 agonists (e.g., Trulicity, Ozempic, Mounjaro, Victoza)
• SGLT2 inhibitors (e.g., Invokana, Farxiga)
• Thiazolidinediones (e.g, Avandia, Actos)
• Sulfonylureas (e.g., glipizide, glimeperide)

For most individuals, metformin is the initial drug choice and can be combined with most other drug options. If, however, you can't tolerate it, as mentioned, there are many other options available.

Again, it's tough to give specific guidance as everyone's medical situation is different, but most commonly GLP-1 agonists are recommended after metformin since they lower blood glucose well, are associated with weight loss, and have evidence for improved cardiovascular outcomes.

I recommend you speak to your doctor to discuss what option is right for you.

Final Words

I hope this answer provided some of the information you were looking for. Thanks for reaching out!