Written by Dr. Phoebe Howells. Reviewed by Jenny Wordsworth. Dr. Phoebe has been a doctor since 2012 with a decade of experience in Obstetrics and Gynaecology focusing on fertility. She's undertaken a clinical fellowship in Reproductive Medicine at a top London fertility clinic alongside authoring articles, sharing insights at global conferences, contributing to fertility trials for women with adenomyosis and working as the Co-Chief Medical Officer for OVUM. 

Fertility involves a complex interplay of hormones and various lifestyle factors, with one crucial element often not considered: glycaemic control. Essentially, this refers to how effectively the body manages blood sugar levels. In this blog, we aim to delve into how fluctuations in blood sugar can significantly impact reproductive hormones, which in turn can affect fertility

Understanding Glycaemic Control

The number of people globally with diabetes was estimated at 9.3% in 2019; however, the prevalence of people having abnormal blood glucose, also known as ‘impaired fasting glucose,’ that isn’t severe enough to meet the diagnostic criteria for diabetes was estimated to be 22% in 2016. Bearing in mind that this includes all age groups, not just those in their reproductive years, you can see that it is still high.

Glycaemic control refers to the management of blood sugar levels within a healthy range. This is particularly crucial for individuals with conditions like insulin resistance or diabetes, but it is key for all of us. When blood sugar levels are consistently high or poorly managed, they can lead to reduced fertility.

So how does poor glycaemic control impact fertility?

In people whose sex was recorded female at birth

Firstly, it can lead to irregular menstrual cycles and, in some patients, anovulation (lack of ovulation). We see this a lot in patients with Polycystic Ovarian Syndrome (PCOS), and there is a known link between PCOS and poor glycaemic control.

High insulin levels can also lead to an increase in androgens (male hormones) in women and people, which can further interfere with ovulation and menstrual regularity.

Insulin resistance, as seen in those with Type 2 Diabetes (where you are producing insulin, but consistently high blood glucose has led to your body being less sensitive to insulin), can also lead to a disruption in the metabolic processes in the ovary. This can result in DNA damage and poorer egg quality.

In people whose sex was recorded male at birth

Men and people with insulin resistance often experience lower testosterone levels, which can impact sperm production and overall reproductive health. Research suggests that poor glycaemic control can lead to decreased sperm quality, with reduced motility and morphology, decreasing the chances of successful fertilisation.

It Works Both Ways

It’s essential to recognise that the relationship between glycaemic control and fertility is bidirectional. While poor blood sugar management can affect reproductive hormones, fertility challenges can also lead to stress and lifestyle changes that exacerbate blood sugar issues. Therefore, addressing glycaemic control can be a pivotal step in improving fertility outcomes.

Strategies for Optimising Glycaemic Control

• Balanced Diet: Emphasise foods that are minimally processed and close to their natural state, including fruits, vegetables, lean proteins, and healthy fats. Avoid processed foods high in refined sugars and unhealthy fats, which can lead to spikes in blood sugar.
• Regular Exercise: Physical activity helps improve insulin sensitivity and can aid in maintaining a healthy weight, both of which are crucial for glycaemic control.
• If Diabetic or Pre-diabetic, Monitor Blood Sugar Levels: Regularly checking blood sugar can help individuals understand how their diet and lifestyle choices impact their glucose levels. If pre-diabetic, you will likely have a yearly check-up with your GP.
• Stress Management: Chronic stress can negatively impact blood sugar levels and hormonal balance. Practices such as mindfulness, yoga, and meditation can be beneficial.
• Consult Healthcare Professionals: Working with healthcare providers, including dietitians and endocrinologists, can provide tailored strategies for managing blood sugar and improving fertility.

Key Takeaways on Glycaemic Control

Most women and people seeking preconception care or fertility services do not have diabetes, prediabetes, obesity, or PCOS. This does not mean that their metabolic health does not influence their fertility. It also does not mean that general lifestyle interventions would not benefit many of these apparently healthy people. When it comes to fertility, keeping blood sugar levels in check might be one of your best-kept secrets. By understanding how blood sugar levels interact with reproductive hormones, you can take practical steps to improve your fertility and improve overall health. Whether you're dreaming of growing your family or navigating challenges along the way, focusing on glycaemic control through balanced meals, regular movement, and managing stress can make a real difference.