I have PCOS and I’m confused about Metformin..
Written in association with:
Obstetrician - gynaecologist
Published: 07/05/2020
Edited by: Cameron Gibson-Watt
The most common medication used in women with polycystic ovary syndrome (PCOS) is the insulin-sensitizer Metformin.
For women with PCOS, their bodies are producing more male hormones, which can result in irregular menstrual cycles, or may even stop menstruation altogether. Metformin treatment, however, can lower insulin and blood sugar levels in women with PCOS, stimulating ovulation and encouraging regular monthly periods.
For many women though, knowing its side-effects and how much it contributes to weight loss can be quite confusing. One of our top consultant gynaecologists and experts in women’s health, Mr Mahantesh Karoshi, clears this all up for us.
Fast facts
Women with PCOS are commonly insulin resistant, meaning their bodies can make insulin but can't use it effectively, which increases their risk for type 2 diabetes. More than half of women with PCOS will develop type 2 diabetes by the age of 40 if they have weight issues. Women with PCOS are more insulin resistant than weight-matched women who do not have the syndrome. Insulin resistance is seen in approximately 10% of slim and 40% of obese women with PCOS. The more the overweight an individual is the greater the degree of insulin resistance. Maternal weight can have a profound effect on both natural and assisted conception, influencing the chance of becoming pregnant and the likelihood of a healthy pregnancy.
Insulin resistance
As a result of insulin resistance in PCOS, circulating insulin levels rise. In the ovaries, high levels of circulating insulin can contribute to excess male hormone production and the absence of ovulation. Simple screening tests, such as fasting blood glucose, can help rule out the presence of insulin resistance if it is less than 5.2 mmol/l.
What does Metformin do for PCOS?
Metformin enhances the sensitivity of insulin. Hence, it is logical to anticipate that insulin lowering and sensitising treatments, such as Metformin, can improve symptoms and reproductive outcomes for women with PCOS.
Metformin inhibits the production of sugar from the liver, decreases fat production, increases the burning of fat and inhibits new glucose molecule formation. This results in a decrease in circulating insulin and glucose.
Can Metformin cause weight loss?
A short survey conducted on Mr Karoshi’s Instagram: 61% of followers believe that Metformin can help women to lose weight
Metformin alone does not help to achieve weight loss in women with PCOS and obesity. Therefore, lifestyle improvements and supporting women with individualised assessments, setting goals and using a combination of diet and exercise remain the first-line approach.
Once this approach has shown weight loss, then adding Metformin at that time has shown to be beneficial rather than starting the medication as a sole agent to cause weight loss, which is not beneficial. In other words, a patient's motivation to lose weight has to be established before starting Metformin by diet, exercise and will power.
Does combining Metformin with Clomid or Letrozole help with fertility?
A short survey conducted on Mr Karoshi’s Instagram: 82% of followers believe that combining Metformin and Clomid or Letrozole can increase their chances of conception
As a first line therapy for the treatment of women who are anovulatory (lack of ovulation) and infertile with PCOS, Metformin alone is significantly less effective than Clomiphene Citrate alone.
If you have a BMI greater than 35 and a clomiphene citrate resistance, you may see a potential benefit from the combined use of Metformin with Clomiphene Citrate.
If I fall pregnant while taking Metformin, is it safe to continue the medication?
A short survey conducted on Mr Karoshi’s Instagram: Followers showing a mixed reaction to whether you should continue Metformin if you fall pregnant
Metformin appears to be safe in pregnancy, however, the usual advice is to discontinue post conception with the exception of those with existing diabetes.
The usual dose of Metformin is 850mg twice daily. It can potentially lead to unpleasant side-effects such as:
nausea vomiting abdominal bloating diarrhoea dizziness unusual tiredness
Can Metformin cause a vitamin B12 deficiency?
You should be aware that there is a strong association between Metformin treatment and decreased vitamin B12 levels in patients with PCOS. This is particularly prevalent in women with weight issues and hyperinsulinemia. The increase in a body chemical called homocysteine could be due to the decrease in its essential co-factors - folic acid and vitamin B12. Research has shown that the long-term use of Metformin in high doses (1500mg or higher daily for more than 6 months) can deplete levels of vitamin B12.
A deficiency of vitamin B12 can cause permanent neurological and nerve damage as well as mood changes and decreased energy.
How can I raise my vitamin B12 levels?
The best absorbable form of vitamin B12 is methlycobalimum. Taking this form of the vitamin sublingually (under the tongue) is recommended. It is also recommended that patients who take Metformin have their vitamin B12 levels checked before the start of therapy and a year later.
If you are still unsure of Metformin, book an e-Consultation with Mr Mahantesh Karoshi by visiting his Top Doctors profile and checking his availability.