The Research: “Normal” Blood Sugar Can Still Impact Fertility

A fascinating study of 117 males revealed something that challenges the way we think about “normal” test results. Researchers found that men with minimally elevated blood sugar levels – with HbA1c readings still well under the 6.5% threshold used to diagnose diabetes – had noticeably reduced sperm motility compared to those with optimal blood sugar levels.

This isn’t about disease. This is about optimisation.

The findings suggest that even subclinical elevations in blood sugar – the kind that get dismissed as “fine” or “nothing to worry about” – can quietly impact the quality of sperm and, ultimately, the ability to conceive.

Why Blood Sugar Affects Sperm Health

So why does blood sugar matter so much for male fertility? Here’s what happens at a physiological level:

Impaired Sperm Motility

Sperm motility refers to how well sperm can swim – and this is absolutely critical for conception. Even if sperm count is normal, if sperm can’t move efficiently to reach and fertilise the egg, conception becomes far more difficult. Elevated blood sugar has been directly linked to reduced motility, meaning sperm struggle to make the journey they need to make.

Oxidative Stress & DNA Damage

High blood sugar creates oxidative stress throughout the body, including in the reproductive system. This oxidative damage can harm sperm DNA integrity, which affects not only fertilisation rates but also embryo quality and miscarriage risk. When blood sugar is chronically elevated (even mildly), sperm are exposed to ongoing cellular stress that compromises their health.

Hormonal Disruption

Blood sugar imbalances don’t just affect glucose levels – they affect hormones too. Insulin resistance and elevated blood sugar can disrupt testosterone production and other reproductive hormones in men. Since healthy testosterone levels are essential for sperm production and libido, this hormonal cascade can have wide-reaching effects on male fertility.

Metabolic & Mitochondrial Dysfunction

Sperm are incredibly energy-demanding cells. They need healthy mitochondria (the “powerhouses” of the cell) to generate the energy required for movement and function. When blood sugar regulation is impaired, metabolic and mitochondrial function suffers – and so does sperm quality.

The Problem with “Normal” Test Results

Here’s where things get tricky: many men receive blood test results that fall within the standard reference range and are told “everything’s normal.”

But “normal” isn’t the same as optimal.

Standard reference ranges are designed to identify disease, not to assess whether your body is functioning at its best for conception. A man might have an HbA1c of 5.8% or a fasting glucose of 5.5 mmol/L – both technically “normal” – but these levels may still be affecting sperm health.

When we’re focused on preconception care, we’re not just looking to rule out pathology. We’re looking to create the healthiest possible physiological environment for conception. And that requires a different lens.

Blood Sugar is Modifiable – And That’s Powerful

The incredibly good news in all of this? Blood sugar is one of the most modifiable factors when it comes to fertility.

Unlike some fertility challenges that feel out of your control, blood sugar can be improved – often significantly – with the right dietary changes, lifestyle adjustments, and targeted nutritional support.

This means that even if subclinical blood sugar elevation is affecting sperm health, we have real, tangible tools to address it.

What Optimising Blood Sugar Looks Like

When we work together to support male fertility through blood sugar optimisation, we focus on:

Comprehensive Testing

We test markers like HbA1c, fasting glucose, and sometimes fasting insulin to understand your true metabolic picture. This gives us a baseline and helps us track progress over time.

Dietary Strategy

We create a nutrition plan that supports stable blood sugar throughout the day – balancing macronutrients, choosing low-glycemic foods, and timing meals to avoid spikes and crashes. This isn’t about restriction; it’s about nourishment that works for your body.

Lifestyle Factors

Sleep, stress, and movement all profoundly affect blood sugar regulation. We address these foundational pillars to support metabolic health from every angle.

Targeted Nutritional Support

Certain nutrients like chromium, magnesium, alpha-lipoic acid, and others can help improve insulin sensitivity and blood sugar control. We use these strategically based on your individual needs.

Root Cause Investigation

Sometimes blood sugar issues are linked to other factors like chronic inflammation, gut health imbalances, or hormonal dysfunction. We dig deeper to understand what’s driving the pattern and address it at the source.

Preconception Care for Both Partners

While this blog focuses on male fertility, it’s worth noting that blood sugar matters for female fertility too. Stable blood sugar supports hormone balance, regular ovulation, egg quality, and a healthy uterine environment.

Preconception care is most effective when both partners are involved – because conception is a team effort, and optimising health on both sides creates the strongest foundation for a healthy pregnancy.

When to Consider Testing

You might benefit from blood sugar testing and optimisation if:

• You’ve been trying to conceive for several months without success
• Semen analysis has shown issues with sperm motility or morphology
• You have a family history of diabetes or metabolic issues
• You’re carrying extra weight, especially around the abdomen
• You experience energy crashes, sugar cravings, or brain fog
• You want to proactively optimise your health before trying to conceive

Even if you’ve been told “everything’s fine,” if you’re not conceiving as quickly as you’d hoped, it’s worth looking deeper.

The Bottom Line

Blood sugar isn’t just a diabetes concern – it’s a fertility concern too.

Even subtle, subclinical elevations in blood sugar can impact sperm motility, DNA integrity, hormone balance, and overall reproductive health. And because so many men fall into this “normal but not optimal” category, it’s a factor that’s often missed in standard fertility investigations.

The empowering part? Blood sugar is something we can measure, monitor, and modify. With the right approach, we can bring those levels into an optimal range – not just “normal,” but truly supportive of conception.

If you’ve been told everything looks fine but you’re still not conceiving, or if you simply want to give yourselves the best possible chance, let’s dig deeper together.

Ready to Optimise Your Fertility?

Through comprehensive testing and personalised preconception care, we can identify whether blood sugar is playing a role in your fertility challenges – and create a tailored plan to address it.

Book your appointment here to discover how optimising blood sugar and metabolic health can transform your fertility journey.