diabetes and male fertility

Diabetes is a well-established global health problem affecting around 500 million people. With aging populations, poor diets and a more sedentary lifestyle it is a major concern for health care officials worldwide.

Could it also be playing a role in the decline of male fertility across the world? Definitely!

What is Diabetes?

Diabetes is a serious illness where blood glucose levels remain too high. When we eat, our food is broken down and converted into energy. That energy is either used or stored as fat for use at a later date. The conversion and storage of this energy is reliant on the hormone insulin which is produced and released by the pancreas.

Diabetes can occur for 2 reasons either our body is not producing any insulin (known as type-1 diabetes) or we are not producing enough insulin or the insulin we have is not working effectively (known as type-2 diabetes).

Type-1 diabetes is the result of an autoimmune issue within the body which means the pancreas is not able to produce any insulin. In contrast, type-2 diabetes develops as a result of your body developing so-called insulin resistance and is thus not responding to the stimulation by this hormone anymore or your pancreas produces less insulin than it used to.

Research has shown that the mechanism and type of damage differs depending on which type of diabetes you have with both forms of diabetes seriously affecting a man’s fertility.

How does diabetes affect the body?

The true mechanism of how diabetes affects fertility is not fully understood. However, research shows that it is a very complicated process.

It is well known and well researched that diabetes causes issues with the central nervous system, the endocrine system (hormones) and our cardiovascular system.

Diabetics are more susceptible to issues with neuropathy (nerve damage), blood pressure, heart disease, stroke, kidney problems and other complex health conditions. Research has also shown that diabetes can have a significant negative impact on a man’s fertility and sexual health including issues with erectile dysfunction, sperm quality, sperm DNA fragmentation, hormone imbalance and ejaculation.

Erectile dysfunction and ejaculatory issues

Erectile dysfunction (ED) is a significant issue for many men with diabetes. Approximately 28% of men suffering with ED have diabetes.

It is thought that the issue arises due to the impact diabetes has on the peripheral nerve supply, the cardiovascular system and the functioning of smooth muscles all of which are key components in a man’s ability to gain and maintain an erection. Erections occur as a result of physical or mental stimulation which triggers a response from the brain and central nervous system. Part of the physiological change that occurs has to do with the muscles within the penis. These are triggered to relax allowing blood to flow into the penis which is then trapped to maintain the erection. Where men are suffering with diabetes the function of the nerves, and smooth muscles (a special type of muscles in the body) can be affected making it more difficult for a man to get and maintain an erection.

Unfortunately, the impact on the nervous system and blood supply does not stop there. Further complications occur within the epididymis, the vas deferens and the neck of the bladder. Each of these also rely on smooth muscles to fulfil their role in transporting sperm ahead of and during ejaculation. A key part of their ability to perform their role is the functioning of the mitochondria (the powerhouse of any cell) which is also compromised as a result of diabetes. It is thought that the impact diabetes has on smooth muscle and the mitochondria impacts the function of the epididymis and vas deferens during ejaculation causing lower sperm count and sperm motility.

As diabetes progresses, this further impacts the smooth muscles that control the neck of the bladder. Typically, when a man ejaculates these muscles contract closing off the bladder forcing the semen to be ejaculated out of the urethra. Retrograde ejaculation occurs when the muscles within the neck of the bladder are not working efficiently causing a man’s ejaculate to enter the bladder rather than exiting the penis.

If left untreated, and as diabetes progresses, it is not uncommon for men to become anejaculatory, i.e. unable to ejaculate altogether whether that be through poor functioning of the epididymis and vas deferens or as a result of retrograde ejaculation.

Oxidative stress

Oxidative stress plays a significant role in diabetic patients just as it does with a lot of other conditions that affect male fertility by damaging sperm functions.

It is thought that oxidative stress is the key factor in patients with type-2 diabetes partly due to the increase in inflammation. However, it also plays a significant role in type-1 diabetes.

Oxidative stress occurs when there is an imbalance between free radicals (cells missing 1 electron) and antioxidants (cells with an extra electron) in favour of the free radicals. This leads to cell damage throughout the body as free radicals go about scavenging electrons from other molecules, thereby damaging their structure and functions.

Where there is a higher level of glucose within the blood stream, as seen in diabetic patients, there is a higher level of metabolism occurring. One of the by-products of metabolism is an increase in free radicals. Hence, it follows that high blood sugar leads to a higher metabolic rate which leads to higher levels of oxidative stress.

We know that sperm are exceptionally susceptible to oxidative stress as they are the smallest cells within the body with an especially sensitive cell membrane which due to an extraordinarily high amount of polyunsaturated fatty acids can be more easily oxidized by the free radicals. This is further compounded by the fact that the epididymis, where sperm undergo their final maturation process, has certain receptors which are particularly affected by diabetes and oxidative stress. The result is that diabetic men are more likely to have decreased sperm motility and density, abnormal sperm morphology and generally increased seminal plasma abnormalities.

Oxidative stress also plays a role in causing sperm DNA fragmentation which has also been seen to be increased in men with diabetes.

Obesity and our hormones

Obesity is a problem in its own right but often goes hand in hand with diabetes creating a myriad of issues.

As our western diet turns to more processed carbohydrate and sugar-heavy foods, our likelihood of becoming obese and diabetic is increasing massively.

With sugar levels in our blood being greater than the needs of our body, leftovers get stored as fat. In obese and diabetic men, this fat tends to get deposited around the belly which becomes a major problem.

We have discussed obesity in detail in our article here.

One of the biggest issues that results from obesity is the impact it has on the hypothalamic–pituitary–gonadal (HPG) axis i.e., how the brain, the pituitary and testicles interact. This finely balanced system relies on a complex series of hormones and messages being passed between them to keep our reproductive system in balance. Higher fat levels seem to create a significant imbalance in many of the hormones that play a key role in sperm production including testosterone, inhibin, and oestrogen. Body fat, especially abdominal fat, produces oestrogen and leptin which act on the brain to secrete less gonadotrophin releasing hormone (GnRH), the main hormone that drives the release of follicle stimulating hormone and luteinising hormone, which subsequently promote spermatogenesis. Consequently, the Leydig cells located in the testicles will be less stimulated to produce testosterone. Yet, less testosterone will, in turn, lead to the production of more fat which turns more testosterone into oestrogen. In turn, higher oestrogen levels lead to further fat deposits creating a vicious circle of increased fat and increasing hormone imbalance.

Men with a higher level of fat in their system have lower testosterone levels, higher oestrogen levels and are more likely to have lower sperm counts and sperm concentration which is what is often seen in diabetic men also.

It is also important to understand the role leptin (the fat hormone) plays within the body. Leptin is a hormone that is produced by adipose fat and helps regulate our energy system. As leptin levels rise it signals to your brain that you have enough fat stored and decreases appetite. Equally when the leptin levels are low, it helps stimulate our appetite. Unfortunately, however, in diabetic patients where there are higher levels of insulin this message gets blocked. This in turn leads to an increase in appetite followed by an increase in blood sugar and an increase in insulin further blocking the leptin signals thus creating a further viscous cycle. The results are increased weight gain, increased insulin resistance, increased leptin resistance and further hormonal imbalance impacting sperm health.

Duration of disease

Research has shown that the age of the patient and the length of time that diabetes has been present are key factors in the impact it has on fertility.

Diabetes, if unregulated, is a progressive disease that leads to a steady increase in inflammation, oxidative stress, nerve and blood cell damage as well as further hormone imbalances which can result is serious and complex health conditions.  

Research has shown that men who have diabetes for 5 years or more are more likely to experience fertility issues and this rises significantly after 10 years with older men being more susceptible to the impact of diabetes.

Recognising diabetes

First of all, it is important to recognise the symptoms of diabetes. If you have any concerns, you should speak to your GP.

Signs and symptoms of diabetes could include:

  • Urinating frequently, often at night
  • Increased thirst
  • Weight loss
  • Increased appetite
  • Blurry vision
  • Numbness or tingling in the hands or feet
  • Tiredness
  • Dry skin
  • Sores that heal slowly
  • More infections than usual

Blood tests through your GP will help monitor your blood glucose levels and give you an indication of whether you need to make adjustments to your diet and lifestyle.

What can you do?

One of the most important things any man can do is make sure his diet and lifestyle are not contributing to the risk of diabetes.

There is a plethora of information available online about how to manage diabetes and limit the risks of it.

Key steps include:

  • Avoiding processed and sugary foods including fizzy drinks
  • Limit carbohydrates such as potatoes, pasta and rice
  • Include whole grains within your diet
  • Exercise regularly
  • Lose any excess weight
  • Eat fresh vegetables, nuts, beans and pulses
  • Eat less processed meats
  • Choose healthier snacks
  • Manage alcohol consumption (i.e. avoid binge drinking)

Making dietary changes is not always easy and some people find reducing sugar quite challenging as it is addictive after all.

There are plenty of free resources online but if you need more 1:1 support you might want to consider speaking to a nutritionist about how to make changes. We have an excellent article from nutritionist Melanie Brown on the essential nutrition tips for fertility which you can read here whilst we also have dedicated podcast episode with Melanie on nutrition and fertility.

It is also important to remember that type-1 diabetes can develop at any age. Most advice is aimed at reducing the risks of type-2 diabetes but being aware of other symptoms and the risk of type-1 diabetes is also important. If any members of your family have diabetes, then this may mean you are in a slightly higher risk bracket and should keep that in mind.

As previously mentioned, erectile dysfunction as well as sub optimal semen analysis results can be key symptoms of diabetes. Many men may fall into this category and may not have considered that they have an underlying health issue. It’s imperative that any man who experiences ED or other fertility issues gets a full and thorough health assessment either through their GP or an andrologist.

Research reviewed

Condorelli RA, La Vignera S, Mongioì LM, Alamo A, Calogero AE (2018); Diabetes mellitus and infertility: Different pathophysiological

effects in Type 1 and Type 2 on sperm function. Front Endocrinol (Lausanne) 9: 268

La Vignera S, Condorelli RA, Di Mauro M, Lo Presti D, Mongioi LM, Russo G, Calogero AE (2015); Reproductive function in male patients with type 1 diabetes mellitus. Andrology 3: 1082-1087

Rehman K, Beshay E, Carrier S (2001); Diabetes and male sexual function. J Sex Reprod Med 1: 29-33