Fasting insulin, why do we need to talk about it?

As a Registered Nutritional Therapist, I sit with people every week whose HbA1c looks fine on paper but whose fasting insulin is quietly telling a completely different story. In today’s health landscape, insulin is more than a buzzword; it’s a critical hormone that plays a vital role in your well-being. If you’ve ever wondered about the link between insulin and your energy, weight, or overall health, you’re not alone.

The rise of continuous glucose monitors (CGMs) has brought blood sugar into the spotlight, but understanding fasting insulin is just as crucial, especially if you aren’t diabetic.

This piece walks you through what the test shows, who should ask for it, and what to do with the result. If you’d rather skip ahead and ask a clinician your specific question, you can book a free 20-minute call and we’ll point you in the right direction.

Fasting insulin reveals how well your body manages blood sugar when you’re not actively digesting food. A simple blood test can flag your risk for insulin resistance, metabolic syndrome and cardiovascular disease, long before traditional tests like HbA1c catch any red flags.

Here’s why that matters – HbA1c is a lagging indicator: by the time it shifts, the body has often been compensating for years. Fasting insulin is an early indicator. It quietly tells us the pancreas is working overtime to keep glucose looking normal. That distinction is the whole reason insulin resistance can be reversed when it’s caught early, and so much harder once it has tipped into type 2 diabetes. 

If you want the deeper background on the mechanism, this overview of insulin resistance, how to spot it and how to reverse it is the next read on our blog.

So, why should we care?

High fasting insulin can flag a much wider set of issues than people realise: systemic inflammation, raised cholesterol and small dense LDL, PCOS, fatty liver, and creeping blood pressure. In our modern world of ultra-processed food and sedentary days, insulin resistance has become genuinely common, which is why monitoring this hormone matters.

We see this in clinic every week. Blood sugar, cholesterol and blood pressure look like three different problems on paper. Under the bonnet they share an engine: insulin. We’ve written about that joined-up view in cardio-metabolic health and why blood sugar, cholesterol and blood pressure are the same problem.

If a liver scan, a cholesterol panel or a PCOS conversation has brought you here, your fatty liver, MASLD and NAFLD explained article is the one we usually send next.

I wrote a longer piece for health and wellbeing platform Healf that takes you through the practical side: how to interpret your fasting insulin result, what to ask your GP, and the lifestyle levers that actually move the number. Learn practical strategies to balance your blood sugars, adjust your diet, and incorporate movement into your routine.

If you’d rather have those levers built into a structured plan around your bloods, your meals and your life, that’s what our blood sugar and insulin resistance nutrition programme is designed to do.

Are you experiencing fatigue, weight gain, or cravings? A fasting insulin test could be the key to unlocking what’s actually going on. We’d always recommend testing with the guidance of a registered professional, but in our clinic these are the readers who almost always benefit:

• Tired but wired: you crash between meals, crave sugar mid-afternoon, then can’t switch off at night. 
• Slowly gaining weight around the middle: despite no obvious change in what you eat or how much you move.
• Recent scan or borderline result: fatty liver on an ultrasound, raised triglycerides, a PCOS diagnosis, or an HbA1c that has crept up.
• Family history of type 2 diabetes or heart disease: especially if you want to see trouble years before it shows up on routine bloods.

Lou’s story is a good example of what changes when you actually look. He came off medication after dropping 44 kg, and the work started with getting honest about what his blood sugar and insulin were really doing. You can read Lou’s full success story here.