All About Metformin

For over 20 years, metformin has been the preferred first-line medication for lowering blood sugar in Type 2 Diabetes. Although it was first discovered in Europe in the 1950s, metformin was not initially popular due to its similarity to other medications with significant safety risks. It did, however, start to gain popularity again in the 90s due to its effectiveness at reducing insulin resistance and much better safety profile compared to other medications on the market at the time. In the United States, the medication underwent intense scrutiny and was finally approved in 1995 by the FDA to treat Type 2 Diabetes. Since then, metformin has become the most prescribed medication for Type 2 Diabetes around the world.

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How Does Metformin Work?

Metformin works by decreasing sugar production in the liver, decreasing absorption of sugars in your digestive tract, and increases uptake of sugars to your muscle, thus improving insulin sensitivity. This effectively decreases your blood sugar and A1C (a longer-term measure of blood sugar control). Unlike other medications for Type 2 Diabetes, metformin is not likely to cause low blood sugar (hypoglycemia), as it does not alter insulin secretion. Overall, this leads to a safe and effective medication to help control Type 2 Diabetes.

Side Effects of Metformin

Unfortunately, side effects are one of the main drawbacks to the use of metformin. Gastrointestinal side effects occur in up to 30% of patients, 5% of which find this intolerable enough to discontinue the medication. The most common side effect is diarrhea, though nausea, abdominal pain, and vomiting are also experienced. While these side effects are known to be dose-related, their mechanism has not been fully understood. There are many theories, including increased gut motility, changes to transporters in the gut, and increased bile salt concentrations which could be linked to the increased diarrhea.

Side effects typically present at the initiation of metformin use, and often go away after a few weeks. There are, however, some reports of diarrhea occurring later on in metformin therapy. This can be made worse if your dose of metformin is increased too quickly, if started at too high a dose, and also for individuals using immediate release formulations of the medication. These side effects can be mitigated slightly by increasing the dose very slowly as well as taking metformin with meals. Unfortunately, some people still experience these unwanted gastrointestinal symptoms.

While most people start with metformin, some individuals will switch to other medications if they cannot tolerate these side effects. In this case, there are many other medication options for Type 2 Diabetes.

Metformin vs. Sitagliptin

Sitagliptin is another medication used to treat type 2 diabetes. Studies have shown that it works just as well as metformin at controlling blood sugar levels. In a double-blind study, researchers compared sitagliptin to metformin. The study found that sitagliptin was "non-inferior" to metformin in reducing HbA1C levels, meaning both medications were similarly effective in controlling blood sugar levels.

However, the study also revealed significant differences in side effects. Patients taking metformin experienced gastrointestinal side effects more frequently (20.7%) compared to those taking sitagliptin (11.6%). Specifically, diarrhea was more common in the metformin group (20.9% vs. 3.6%), as was nausea (3.1% vs. 1.1%).

This information suggests that sitagliptin may be a viable alternative for patients who find metformin's side effects intolerable. While both medications are equally effective, sitagliptin tends to cause fewer gastrointestinal issues.

For those concerned about the cost of switching medications, generic sitagliptin is available at Marley Drug for just $80 per month. It comes in 25 mg, 50 mg, and 100 mg tablets, and no insurance is required.