In healthy people, the pancreas (a small gland in the body) releases the hormone insulin to control blood sugar levels after eating a meal. When blood sugar levels are not properly controlled and become too high this is called ‘hyperglycaemia’. High blood sugar levels are linked to an unhealthy lifestyle, particularly being overweight, having a poor diet and a lack of exercise. Our genetics also play a major role. When hyperglycaemia reaches a certain level and persists, the condition becomes type 2 diabetes.
What is type 2 diabetes?
Type 2 diabetes happens when the pancreas can no longer produce enough insulin to control blood sugar levels, or the body becomes resistant to insulin so it stops working. Diabetes can cause many serious health conditions if not properly managed.
What is pre-diabetes?
Pre-diabetes is a condition where the body can’t properly process sugars. In pre-diabetes blood sugar levels are higher than normal but not high enough to be called type 2 diabetes and is sometimes called ‘impaired glucose tolerance’. Pre-diabetes, which can occur without any symptoms, increases the risk of developing type 2 diabetes and heart disease. Lifestyle factors and/or having a family history of diabetes are usually the cause of pre-diabetes.
How does diabetes affect male sexual and reproductive health?
Diabetes can damage blood vessels and nerves, and increase risk of infection, especially when not well controlled. As a result, diabetes is associated with a range of sexual problems including erectile dysfunction, decreased sex drive (libido), ejaculation problems and inflammation of the foreskin (balanitis).
Can diabetes affect male fertility?
The rate of pre-diabetes and diabetes is increasing among young people so any harmful effect on fertility is a huge health concern. It is already known that high blood sugars in diabetic men may lower fertility.
A recent study of men attending a fertility clinic also found that men suspected of pre-diabetes (abnormally high blood sugars) had higher levels of damage to sperm DNA, were more likely to have unexplained azoospermia (no sperm in the ejaculate) and had lower testosterone levels and more disruption of other fertility hormones, compared to men attending the clinic without clinical signs of pre-diabetes. 
More studies are needed to understand if prediabetes affects male fertility in the general population and not just for those who may already have lower fertility. The importance of looking after your health before trying for a baby and making positive lifestyle changes such as eating healthily and getting more exercise should be high on the agenda.
1. Maresch CC, Stute DC, Alves MG, et al. (2018) Hum Reprod Update. 24(1):86-105.
2. Boeri L, Capogrosso P, Ventimiglia E, et al. (2018) BJU Int. In Press
Andrology Australia (www.andrologyaustralia.org) is the Centre for Male Reproductive Health, funded by the Australian Government Department of Health and administered by Monash University.
This information has been provided for education purposes only. It is not intended to take the place of a clinical diagnosis or proper medical advice from a fully qualified health professional. Andrology Australia urges readers to seek the services of a qualified medical practitioner for any personal health concerns.