For more than eleven years, I have watched the same pattern unfold in women during perimenopause.
A woman comes into clinic frustrated because the scale will not move.
She is eating better than she did in her 20s and 30s. She is exercising consistently. She is prioritising protein, reducing processed foods, and doing everything she has been told should work.
Yet her body is no longer responding the way it used to.
Often, she is not diabetic. Many times, she is not even prediabetic. In fact, she may not even be overweight.
But something has changed metabolically.
She has blood tests done. Her fasting glucose is normal. Her HbA1c is normal. She is told her metabolism looks “fine” and that she simply needs to “exercise more and eat less.”
And this is where many women are being missed.
The Missing Piece: Insulin Resistance in Perimenopause
One of the most overlooked markers in women’s metabolic health is fasting insulin.
Most standard blood work focuses on glucose levels — how much sugar is circulating in the bloodstream.
But insulin tells us something entirely different.
Insulin shows us how hard the body has to work to move glucose out of the bloodstream and into the cells where it can be used for energy.
A woman can have completely normal glucose levels while her body is producing significantly more insulin behind the scenes to keep those glucose levels stable.
This is often the beginning of early insulin resistance.
Why Normal Blood Sugar Does Not Always Mean a Healthy Metabolism
One of the challenges with insulin testing is that fasting insulin alone does not always tell the full story.
A woman may fast for 8–12 hours before her blood test and receive a fasting insulin result that falls “within range.”
But this does not necessarily mean her insulin response throughout the day is healthy.
What I frequently see in clinic is this:
- Fasting glucose: normal
- HbA1c: normal
- Fasting insulin: technically within range
- But insulin after meals remains elevated for far too long
This matters because the body should be able to rise and recover appropriately after eating.
In a metabolically flexible woman:
- Insulin rises after food
- Glucose moves into the cells efficiently
- Insulin then comes back down to baseline within a reasonable timeframe
In many women during perimenopause, this no longer happens effectively.
Instead:
- Insulin stays elevated
- Fat storage becomes easier
- Energy crashes increase
- Cravings worsen
- Weight loss becomes significantly harder despite effort
Why I Often Recommend Both Fasting and Post-Meal Insulin Testing
This is why I often prefer to assess two important baselines:
- Fasting insulin
- Insulin two hours after a meal
These two numbers often paint a completely different metabolic picture.
A woman may appear “normal” on standard pathology ranges while still showing signs of early metabolic dysfunction once we assess how her body handles food in real time.
Understanding Optimal vs “Normal” Insulin Levels
Most pathology lab ranges for fasting insulin are broad — often somewhere around:
- 2–25 microunits/mL
But “within range” does not always mean optimal.
In a metabolically healthy and efficient woman, I generally like to see fasting insulin much lower — often closer to:
- 3–5 microunits/mL
And ideally, insulin should return close to baseline within approximately two hours after eating.
In women developing insulin resistance, post-meal insulin can remain significantly elevated — sometimes well above:
- 25 microunits/mL two hours after a meal
This can occur years before prediabetes or diabetes ever appears on routine blood tests.
Why Insulin Resistance Matters in Perimenopause
Perimenopause already creates hormonal shifts that influence:
- Fat storage
- Muscle mass
- Appetite
- Sleep
- Cortisol regulation
- Blood sugar stability
When insulin resistance develops alongside these hormonal changes, women often notice:
- Weight gain around the abdomen
- Increased inflammation
- Fatigue
- Difficulty building muscle
- Intense cravings
- Brain fog
- Reduced response to dieting and exercise
And unfortunately, many women are still being told this is simply “ageing.”
It is not always ageing.
Sometimes it is unrecognised metabolic dysfunction.
If You Feel Like Something Has Changed, Trust That
If your healthcare provider has told you everything looks “normal,” but you still feel like your metabolism has shifted dramatically, it may be worth asking for:
- Fasting insulin
- Post-meal insulin testing
- A more comprehensive metabolic assessment
Because insulin resistance can exist long before diabetes appears.
And for many women in perimenopause, it is one of the hidden drivers behind unexplained weight gain and metabolic frustration.
