Warning to diabetic fathers as study suggests taking metformin while trying for a baby may TRIPLE risk of having a son with genital birth defects
- Study of 1million babies in Denmark show diabetes drug linked with birth defects
- Fathers who take metformin 3-times more likely to have son with genital problem
- And fathers taking the drug are 40 per cent more likely to have child with defect
Fathers who take metformin are more likely to have babies born with defects, new research suggests.
But experts say the risk only exists when men take the cheap diabetes drugs during conception.
Defects were roughly 40 per cent more common among youngsters whose fathers were prescribed the common medication.
And the risk of sons having a genital defect was three times higher, according to the study of 1.1million newborns.
Experts say men taking the diabetes drug who hope to have children should talk to their doctors about whether they should swap medication.
However, the team warned that diabetes itself — a condition suffered by millions of men — also reduces sperm quality and fertility.
Metformin is usually the first drug type 2 diabetes patients are prescribed. It is unclear how many men are prescribed the drug, but 4.7million people in the UK and 37million in the US suffer from diabetes
Metformin is usually the first drug type 2 diabetes patients are prescribed.
It is unclear how many men are prescribed the drug, but 4.7million people in the UK and 37million in the US suffer from diabetes.
The drug controls type 2 diabetes by reducing the amount of sugar the liver releases into the body and brings down blood sugar levels by improving insulin resistance.
Academics at the universities of Stanford and Southern Denmark analysed 1.1million births in Denmark between 1997 to 2016.
They cross-referenced the newborns’ health data with their fathers’ prescriptions of diabetes drugs insulin, metformin and sulfonylureas.
Babies were considered ‘exposed’ to a drug if their father had at least one script in the three months up to conception — which is when the fertilising sperm were developing.
Of all the babies included in the research, 3.3 per cent were born with one or more major birth defects.
WHAT IS DIABETES?
Diabetes is a lifelong condition that causes a person’s blood sugar level to become too high.
There are 2 main types of diabetes:
- type 1 diabetes – where the body’s immune system attacks and destroys the cells that produce insulin
- type 2 diabetes – where the body does not produce enough insulin, or the body’s cells do not react to insulin
Type 2 diabetes is far more common than type 1. In the UK, around 90 per cent of all adults with diabetes have type 2.
The amount of sugar in the blood is controlled by a hormone called insulin, which is produced by the pancreas (a gland behind the stomach).
When food is digested and enters your bloodstream, insulin moves glucose out of the blood and into cells, where it’s broken down to produce energy.
However, if you have diabetes, your body is unable to break down glucose into energy. This is because there’s either not enough insulin to move the glucose, or the insulin produced does not work properly.
There are no lifestyle changes you can make to lower your risk of type 1 diabetes.
You can help manage type 2 diabetes through healthy eating, regular exercise and achieving a healthy body weight.
Source: NHS
But the figure was 5.2 per cent among newborns whose fathers took metformin, the study in the Annals of Internal Medicine showed.
The team said this corresponds to a 41 per cent higher risk, compared to those who did not take it.
Results also showed the chance of having a boy with genital birth defects was three times higher among the sons of paternal metformin-users.
However, fathers who took the drug before or after trying to conceive didn’t have an increased risk.
Metformin is thought to suppress male hormones such as testosterone, and interfere with male reproductive health.
And studies have recorded smaller testicle size and less testosterone secretion in the offspring of male rats who are exposed to metformin.
Meanwhile, fathers on insulin had no increased risk of having a baby with any defect, compared to fathers who did not take the drug.
There was not enough data on fathers who took sulfonylureas to determine whether they were at an increased risk.
The experts said the ‘sheer size of the diabetes pandemic’ suggests the treatment of prospective fathers with diabetes should be further studied.
Professor Allan Pacey, an andrologist at the University of Sheffield and former chair of the British Fertility Society, who was not involved in the study, said metformin is ‘a commonly used drug in men of reproductive age’.
So the findings raise questions about whether men taking the drug and planning to start a family in the near future should be concerned,’ he said.
‘This should be discussed with their family doctor or the diabetes specialist who is looking after them,’ Professor Pacey added.
Diabetes itself can affect male fertility so it is important that men ‘take some form of medication rather than stop their metformin altogether’, he noted.
Dr Channa Jayasena, an andrologist at Imperial College London, said the findings are surprising, noting that insulin is a stronger medication than metformin.
He said: ‘The authors cannot exclude that men on metformin had worse control of their diabetes.
‘So, the results are thought-provoking but inconclusive. Men with diabetes should not be dissuaded from taking metformin, but this is worth looking at more closely.’
Professor Sheena Lewis, an expert in reproductive medicine at Queen’s University Belfast who was not involved in the study, noted that the study did not examine how well the men regulated their diabetes, with poor management having a damaging impact on sperm.
She said: ‘As couples wait until older before starting families, their chances of being on medication for other chronic illnesses increases.
‘The take home message is that men who are trying to have children should discuss all other medications with their family doctors to ensure these have no known adverse effects on male fertility.’
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