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New research suggests a surprising link between the use of diabetes drugs like Metformin and the risk of developing multiple sclerosis. Maskot/Getty Images
  • MS is an autoimmune disease that attacks the central nervous system.
  • It can lead to disabling symptoms such as fatigue and problems walking.
  • MS has been linked to type 2 diabetes, leading scientists to look at repurposing diabetes drugs to treat it.
  • A new study has found that taking diabetes drugs was associated with a reduced risk of MS if taken by people under the age of 45.
  • However, these medications were associated with an increased risk of MS in people over 45, especially women.

Recent research published in the journal Heliyon suggests that the usage of diabetes drugs like insulin and metformin could potentially help reduce the risk of developing multiple sclerosis (MS).

The scientists found during their study that exposure to anti-hyperglycemic medications was linked with a reduced incidence of MS in T2D patients under the age of 45.

However, exposure was associated with an increased risk for the disease in people over the age of 45, especially in women.

According to The National Multiple Sclerosis Society, multiple sclerosis (MS) is an autoimmune disease in which the immune system attacks the central nervous system (CNS)

The CNS is made up of the brain, spinal cord, and optic nerves.

When the immune system attacks the CNS, it destroys a fatty protective layer surrounding nerve fibers called the “myelin sheath,” leaving the nerve fibers susceptible to damage.

Among its common symptoms are:

  • muscle spasms
  • fatigue
  • walking difficulties
  • numbness or tingling

MS cannot be cured. Treatment focuses on controlling symptoms and slowing the course of the disease.

It is unknown what causes MS, although it could be a combination of things, such as environmental factors, infections, or genetics.

Scientists have also noted that there seems to be some sort of relationship between having MS and type 2 diabetes (T2D), although according to Dr. Daniel Harrison, a neurologist, and Director of the University of Maryland Center for Multiple Sclerosis, it is a weak association with no clear biologic link being established.

It has additionally been found that people with T2D who receive antidiabetic drugs like metformin have improved MS symptoms, leading to speculation that metformin and other diabetes treatments could be repurposed as MS medications.

In order to examine the issue, a team of scientists led by Dr. Gregory L. Branigan at the University of Arizona in Tucson conducted a study looking into how the use of drugs like metformin might affect people’s risk for developing MS.

“There is mounting evidence linking metabolic disorders and MS through a common driver of increased autoimmunity, which brings into question the impact of the therapeutics used to treat T2D on the incidence of MS,” the authors wrote.

Harrison, who was not a part of the study, explains that the authors were not looking at the diabetes drug, per se, as a preventive agent. Rather they were looking at whether treating diabetes with medications versus diet would influence people’s risk of developing MS.

“They were inspired to evaluate this because of some of the studies showing weak associations between the incidence of both diagnoses in patients and some preliminary work, mostly in animal models, showing that some diabetes treatments (mainly metformin) might have an anti-inflammatory effect,” said Harrison.

The researchers selected over 5 million people from the Mariner insurance claims database to participate in the study, with over 1.5 million of these remaining in the final analysis.

People who had used anti-hyperglycemic medications to treat their T2D — such as insulin and metformin — were compared to those who had not.

It was found that people who took the medications had a 22% lower risk of developing MS during the follow-up period — if they were under the age of 45 when they first began treatment.

On the other hand, people who were older than 45 years when they first initiated drug therapy had a 16% greater risk of developing the disease.

When looking at the impact of sex assigned at birth on both age groups, in patients younger than 45, both women and men treated with diabetes medications had a reduced risk for the development of MS. In those over 45, men had a slightly significant increase in MS risk, while women had a significant increase.

“The ratio of women to men with MS is typically found to be about 2-3 to 1,” noted Harrison. “There are myriad factors that cause this difference, mostly having to do with how the different sex hormones in men and women regulate the expression of certain genes for immune system and nervous system function.”

“The association between diabetes treatments and MS risk was no different in men versus women in this study,” he explained.

Harrison said since this particular study is retrospective — meaning that it is looking at historical records — it can be difficult to isolate the risk factor that you want to look at from other factors that might also be playing a role.

“The strongest such concern comes from the fact that those who treat their diabetes with diet alone are inherently going to be very different than those who use medications,” said Harrison.

“The severity of their underlying diabetes is different. Their overall health, diet, weight, exercise, cigarette smoking, and other lifestyle factors and behaviors is going to be very inherently different. Their underlying genetics will clearly be different, also leading to those differences in ability to control diabetes with diet alone versus needing medications.”

Harrison said it is impossible to know if the findings from the current study really indicate anything about diabetes treatments or if they stem from one of the aforementioned factors.

“I do not think that this study provides evidence that suggests anyone should do anything different at this time,” he added. “Specifically designed and controlled studies would need to evaluate this question before any conclusions.”

Dr. Achillefs Ntranos, a neurologist and MS specialist, based in Beverly Hills, California, shared Harrison’s concerns about the retrospective nature of the study, saying that it is not clear at this point whether people should change their approach to treating diabetes.

“However, these findings emphasize the need to treat type 2 diabetes early to prevent any potential complications down the road, as they can be detrimental to one’s health,” said Ntranos. “A trial of diet and exercise to control diabetes should also be done first before trying any medications, as that can have many other beneficial effects on the body.”

Ntranos further advised that the potential increased risk for developing MS observed in the study should not be factored into treatment decisions.

“MS is not a very common disease in the general population, and even if a patient is doubling their risk for MS, the actual chance of developing it is still quite low. Priority should be therefore placed in controlling diabetes, as that can have far greater and more imminent consequences for one’s health.”