If you’ve had your fasting glucose and HbA1c (2 to 3 month average blood glucose reading) tested and got the all-clear, but your doctor hasn’t also tested your fasting insulin, it might be worth asking for a more comprehensive blood panel. There are other markers to consider too, but insulin is such a vital part of the metabolic picture. It blows my mind that it isn’t a stock-standard test! 🤯
Insulin only popped onto my radar when I started digging deep into metabolic health. I had NO idea it was such a pivotal hormone, playing a role in blood glucose regulation, energy production, energy storage, fat storage, brain function, reproductive health, and more. It affects virtually every cell in your body.
Before that, I really only understood it as something related to diabetes. Essential to life for people with type 1 diabetes, and necessary for blood glucose regulation in people with type 2 diabetes.
Boy, was I lacking in critical information!
What is insulin?
Insulin is a key player in metabolic health and, in my opinion, one of the most overlooked aspects. Carbohydrates have the biggest effect on insulin, since they convert into glucose quickly, though protein and fat also play a role in how much insulin a meal produces overall.
Whenever we eat carbohydrates, they’re broken down into glucose, which enters the bloodstream. Your body works hard to keep blood glucose within a very narrow range, with only about 5 grams (roughly one teaspoon) circulating in your entire bloodstream at any one time. In response to the glucose hitting your system, your pancreas releases insulin, often within minutes of eating. Its primary job is to shuttle glucose out of the bloodstream and into your cells, where it can either be burned for energy or stored for later use, as glycogen in your liver and muscles, and as fat.
Insulin also helps us build muscle and grow. Pregnancy and puberty are times when we’re naturally insulin resistant (makes sense as we’re growing stuff!).
Why insulin matters?
While insulin, often dubbed the storage hormone, is elevated, your body is in storage mode and is much less willing to release stored fat for fuel. That’s one of the reasons chronically high insulin can make fat loss feel like such an uphill battle.
The problem isn’t insulin itself though. The problem is when it stays elevated for long periods of time.
Because insulin affects virtually every cell in your body, chronically elevated insulin doesn’t just influence body weight. It can also affect your energy levels, hunger, cravings, blood pressure, reproductive health, liver health, inflammation, and long-term metabolic health.
What is insulin resistance?
Over time, if insulin stays high, your cells stop responding to it as effectively. To compensate, your pancreas produces even more insulin to keep your blood glucose under control (this is vital for survival). This is called insulin resistance, and it’s a vicious cycle.
Did you know that insulin can be elevated for years before blood glucose and HbA1c start to rise? That means you can be developing insulin resistance while your standard diabetes screening tests stay within range. By the time someone is diagnosed with pre-diabetes or type 2 diabetes, insulin resistance has often been developing for years.
Why should we care?
Research suggests insulin resistance plays a central role in many chronic diseases and is strongly associated with high blood pressure (hypertension), polyendocrine metabolic ovarian syndrome (PMOS, formerly known as polycystic ovary syndrome or PCOS), cardiovascular disease (including coronary artery disease, heart attack and stroke), type 2 diabetes, metabolic dysfunction-associated steatotic liver disease (MASLD, formerly known as non-alcoholic fatty liver disease or NAFLD), Alzheimer’s disease (sometimes referred to by some researchers as ‘type 3 diabetes’), infertility, and more. It’s important to remember that while insulin resistance is strongly associated with these conditions, it isn’t the sole cause.
Frequently eating more energy than your body needs, grazing throughout the day, diets high in refined carbohydrates, limited physical activity, and chronic stress can all contribute to insulin resistance.
Signs and symptoms
You may not have any symptoms (or you’re good at ignoring the noise your body is making 
), but if you notice any of the following, you might want to test fasting insulin as well as glucose.
〉energy crashes/afternoon slumps
〉constant hunger
〉sugar cravings
〉weight gain, particularly around the middle
〉brain fog
Lean individuals can also develop insulin resistance; you don’t have to be overweight to have poor metabolic health.
The good news
Insulin resistance is often very responsive to lifestyle. Our bodies are incredibly adaptable, and even small, consistent changes can have a big impact over time.
The food we eat, how much we move, our sleep, stress levels, and body composition all influence insulin sensitivity. Avoiding highly processed and refined foods, reducing carbohydrate intake where appropriate, incorporating periods of fasting into your day, building muscle through resistance training, walking after meals, prioritising quality sleep, and managing stress can all help.
You don’t have to overhaul your entire life overnight. It’s about getting educated, understanding why these changes matter, and making small, sustainable changes with commitment and consistency. Once we have our ‘why’, we’re far more likely to feel intrinsically motivated and, ultimately, succeed.
Stick around and you’ll learn so much more about insulin, and how to modify your lifestyle to improve your health.
