No, Metformin Isn’t Just for People With Type 2 Diabetes

Editor’s note: This article shares Ginger Vieira’s personal experience using Metformin along with her daily insulin as someone with type 1 diabetes (T1D). Remember, Ginger is not a doctor, and she’s not your doctor. What worked for her might not work for everyone.  Do not make adjustments to your diabetes care plan without talking to your HCP first. If you think Metformin could help you manage diabetes, definitely talk to your health care team!

I’ve lived with type 1 diabetes (T1D) for almost 25 years. About five months ago, I started taking Metformin. At first, the impact on my insulin sensitivity was minimal. But the longer I’ve been taking it, the more I experience the benefits.

Spoiler alert: I’ve been able to stop that early morning spike in my blood sugar from the dawn phenomenon. Plus, I even lost six pounds of stubborn weight that I couldn’t get rid of with my other healthy habits.

But it’s not just about weight! Metformin has impacted my T1D management in several important ways.

Metformin research in people with T1D

First, let’s cover some basics and research around the use of Metformin in people with T1D.

Yes, Metformin is usually prescribed in people with type 2 diabetes (T2D), not type 1 diabetes. Still, it’s not off-limits for people with T1D like me. It can be helpful in several ways when taken alongside your basal and bolus insulins. 

The benefits of Metformin in T1D have been studied. In a 2018 report, 29 adults with T1D who had Metformin added to their insulin therapy for 12 months were compared with 29 adults with T1D who remained on insulin therapy alone. 

The results were fascinating:

• Researchers found that Metformin lowered blood sugar levels, reduced the risk of metabolic syndrome and that participants taking Metformin needed less insulin than those using insulin alone after a year of treatment
• Results didn’t depend on changes in blood lipids or weight loss, although, on average, people lost weight with Metformin and insulin therapy. In contrast, the average participant’s weight went up with insulin alone

Overall, most studies of T1D and Metformin have included a small number of participants and more research is needed. 

Other uses for Metformin

Metformin is used in T2D, off-label in T1D and also for people without diabetes. Let’s look at a few of its benefits unrelated to diabetes. 

There are many benefits of Metformin unrelated to diabetes:

• Metformin is commonly used for polycystic ovary syndrome (PCOS).
• Metformin can help weight-related conditions (like metabolic syndrome).
• Metformin can support weight management in people living with obesity, even if they don’t have diabetes.
• Metformin studies show a strong benefit in reducing numerous cancers and related deaths, although these studies have not consistently been reproduced in humans or animals. 
• Metformin may also improve fertility for those having trouble getting pregnant by reducing insulin levels in the bloodstream and promoting egg release from the ovary (ovulation). 
• Metformin has been linked to improvements in cholesterol and heart disease.

While these benefits are impressive, let’s be very clear—Metformin cannot replace insulin for people with T1D. It is meant to help your insulin and might even reduce how much insulin you need, but it will never fully replace insulin. 

5 ways Metformin works for people with T1D

1. Metformin can help when your body doesn’t produce enough of the hormone amylin: Amylin is an important hormone made by the pancreas, except in people with T1D. In T1D, the immune system attacks the cells in the pancreas that make hormones. These cells normally produce insulin, which is made by beta cells, and amylin, made by alpha cells. Amylin helps in several ways: it lowers the amount of sugar your liver makes, signals to your brain that you’re full during and after eating and helps prevent blood sugar spikes after meals by slowing down digestion.
2. Metformin reduces the amount of glucose (sugar) that your liver produces: Your liver releases stored glucose (known as glycogen) drip-by-drip all day long. By reducing your liver’s glucose production, you’ll also reduce the amount of basal (background) insulin your body needs. The less glucose we produce and the less basal insulin we need, the less likely we are to store excess glucose as body fat. Remember, this can also apply to morning liver glucose levels triggered by dawn phenomenon hormones. If your body doesn’t make enough amylin, it causes your liver to produce more glucose than it normally would.
3. Metformin reduces your appetite and reduces post-meal spikes in your blood sugar: It does this by slowing down how quickly your stomach empties digested food into your small intestines, where the glucose then enters your bloodstream. By slowing down this process, Metformin can curb the post-meal spike you’ve battled with pre-bolus insulin and stress! This also inevitably decreases your appetite by helping you feel full sooner and longer after eating. 
4. Metformin reduces how much glucose you absorb from the food you eat: By blocking how much glucose you absorb from digested food, it reduces how much glucose affects your blood sugar. This clearly affects how much insulin you need for the food you eat. 
5. Metformin increases your body’s sensitivity to insulin: Whether that insulin was produced by your own pancreas or delivered via injection or pump, it increases your cells’ ability to use it. This means your insulin will work better for you and you may need less insulin overall. 

What are the cons of taking Metformin? 

One possible downside of taking Metformin long term is that it can cause a vitamin B12 deficiency. This isn’t a reason to avoid Metformin, but it does mean that you should consider routinely working with your healthcare provider (HCP) to check your B12 levels and seek advice on taking a B12 vitamin supplement. 

Metformin can also cause side effects in some people, which we’ll dive into next.

7 tips for taking Metformin 

Between potential side effects and the positive impact Metformin can have on your diabetes, here are a few things to keep in mind while taking Metformin if you have T1D. Many of these tips also apply to taking Metformin with T2D.

1. Metformin can cause digestive side effects in some people: Some people may feel queasy, have diarrhea or need to use the bathroom more often. You might also experience bloating or gas. I had a couple of days where I went to the bathroom a bit more than usual, but it was mild. For many people, these side effects go away after a few weeks, while others might continue to experience them. To help reduce side effects, it’s a good idea to start with a low dose, like 500 mg. Work closely with your HCP to increase your dose of Metformin. Also tell them if you have side effects so you can explore your options together, like trying the extended-release version.  Pro tip: Not everyone will have side effects like digestive issues, but some people find it helpful to take Metformin with food, not on an empty stomach
2. Metformin is more helpful the longer you take it: Patience and consistency are critical! In my experience, Metformin can take a little while to really get going, so stick with it for at least  three months before deciding how effective it is for you. Communicate with your  HCP about your results, and especially if you have any questions, as you go through this process. They can help you along the way.
3. The timing of your Metformin matters, even with the extended release version: It’s usually recommended to take medication with meals, 
4. Metformin can lead to lower blood sugars and may require immediate and long-term changes to your insulin doses: Yes, if you start taking a blood-sugar-lowering medication with your insulin, you may need to watch for the impact on your blood sugar and any lows. Metformin is not widely known for causing low blood sugars. If you experience recurring low blood sugars and your routine and health status are stable, this means it’s time to adjust your insulin doses with support from your health care team. 
5. Metformin limits your liver’s ability to make more glucose and how your body digests food , which may impact how you dose insulin: In my experience, Metformin can delay the impact of a meal on my blood sugar by at least 30 minutes, sometimes more. This means I need to adjust how I take my insulin, too, because I don’t want the insulin to hit before the food does. When taking large doses for high-fat/high-carb meals (like pizza, cupcakes, etc.), this is especially important for me to keep in mind.
6. Metformin’s weight effect is debatable: This is definitely not a weight-loss drug and is generally considered a weight-neutral medication, but some people may lose a small amount of weight. The combination of decreased liver glucose, decreased insulin and decreased sugar absorbed from food can support potential weight loss. It was only after three months that I personally noticed I was losing  weight, and near the end of five months, I’m almost down six pounds of stubborn chub that no amount of jumping rope, jogging and clean eating would budge.
7. Metformin is one of the cheapest drugs on the planet: Metformin costs me about $3.61 per month out-of-pocket. I would’ve loved to try something more powerful than Metformin—like Ozempic (semaglutide)—but my insurance company said I didn’t qualify. So, I asked my doctor for a prescription for Metformin to address my rising insulin needs with the hope that it might impact my dramatic dawn phenomenon, too. While he wasn’t experienced in prescribing it for T1D, he agreed that it could be helpful. My insurance didn’t believe I had enough insulin resistance to qualify for Ozempic, but they easily approved my request for Metformin to address the same issue.

My health journey: What happened after I took Metformin for 5 months

Before taking Metformin, here were my health stats:

• Weight: 127 pounds, at a height of 5’2”—I had slowly crept up to this over the course of the last year.
• A1C and goal range: 5.7 to 6.3%
• Long-acting insulin dose: 15 units—rising from nine to 11 units just a year before.
• Insulin-to-carbohydrate ratio: 1:10 to 1:15—one unit of insulin for every 10 to 15 grams of carb.
• Dawn phenomenon spike: Hits at six o’clock a.m. and spikes 100 to 150 points. I need one unit of rapid-acting insulin, carefully timed around my morning exercise, to prevent that dramatic spike.

After taking Metformin for five months, I saw changes in my health stats:

• Weight: 121 pounds, at a height of 5 foot, 2 inches—a slow and steady loss that wasn’t visible until after three months
• A1C: still in my goal range of 5.7 to 6.3%
• Long-acting insulin dose: ten units—a significant reduction, back to my usual baseline
• Insulin-to-carbohydrate ratio: 1:30—one unit of insulin for every 30 grams of carbohydrate—I need significantly less insulin for my meals
• Dawn phenomenon spike: I rise only about 30 points when I first wake up. I don’t see a more dramatic rise until 9 a.m. if I choose to practice intermittent fasting and skip breakfast—if you don’t eat breakfast,  my liver releases stored glucose to give me energy.  I no longer worry about dropping low during morning fasted exercise!

Be patient and consistent with Metformin

At first, I didn’t really notice how Metformin was changing my insulin needs. But I’m glad I kept taking it because after five months, I could really see how much it helped. Metformin has made a big difference in my insulin needs, weight, appetite and morning glucose production.

From my experience, I believe that Metformin may be beneficial for people with T1D. It’s also an inexpensive medication. If you think Metformin could help you manage diabetes, definitely talk to your health care team!

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