For a woman who reaches menopause at 50, her hormones start changing course at around 35. That's one of the headline findings from a study published in Nature Medicine this month, and it moves the timeline most of us were given by about seven years. The researchers analysed more than 300 million blood tests from over a million women in the US and Israel, and described what happens at the final period as a physiological cliff: a sudden shift across liver, cholesterol, bone and kidney markers, with the hormones beginning to drift more than a decade before.
If you're in midlife and trying to make sense of changes in your energy, weight or sleep, this is worth understanding. It also raises a fair question about what a glucose monitor can show you during these years, and what it can't.
How do you study menopause when nobody wrote down the date?
Most big health datasets never record when a woman had her last period, so menopause gets smeared into age. A 52-year-old could be five years past it or two years away, and averaging them together blurs everything into a gentle slope.
The team at the Weizmann Institute in Israel borrowed a technique from astronomy, the maths used to sharpen a blurry telescope image, and used it to line up millions of results by time to menopause instead of by birthday. They checked it against SWAN, the long-running American study that has followed women through the transition for decades, and the two matched closely for the key hormones.
Then they ran exactly the same analysis on men, treating 50 as a pretend menopause. Men's results drifted gradually with age, with no step at all.
What changes at the final period
Of the 90 blood tests studied, 52 showed a significant jump in women compared with men. The sex hormones moved most, as you'd expect, but the reach of the change was the striking part. Bone density fell sharply. Liver enzymes such as ALT and GGT rose. So did total cholesterol, LDL, triglycerides and apolipoprotein B, along with markers of kidney function and fluid balance. The US and Israeli datasets agreed with each other remarkably well, despite completely different populations and healthcare systems.
Most of these shifts point in the direction of higher disease risk. Iron was the exception: once periods stop, iron and red blood cell markers improve, and anaemia becomes less common. After menopause, osteoporosis climbed far faster in women than in men, and rates of heart attack and stroke accelerated. Depression scores and sleep problems, including trouble falling asleep, rose in the year or so after the final period and then eased back towards the slower pattern seen in men.
The hormones start moving 12 to 15 years earlier
The cliff has a long run-up. On average, anti-Müllerian hormone (AMH) began falling faster about 15 years before the final period, FSH began rising faster about 14 years before, and oestradiol began dropping faster about 12 years before. Standard guidance tends to talk about a three to seven year transition, so this pushes the start of the story back into the late thirties for many women.
These are population averages. They can't tell any one woman where she is on the curve, and the researchers are clear that their method maps trends across a population; it doesn't predict anyone's menopause date.
Where glucose fits
In this study, fasting glucose, HbA1c, two-hour glucose tolerance and fasting insulin all rose steadily with age in women and men alike, with no obvious cliff at menopause.
That tells us two useful things. Menopause doesn't flip a switch on fasting blood sugar the way it appears to for bone density or cholesterol. And a fasting reading is exactly the kind of snapshot that misses what happens across an ordinary day: after a meal, after a bad night, in the middle of a stressful week. This study didn't measure glucose through the day, so it can't say whether glucose variability changes around menopause. That question is still open, and it's an important one.
What we can say is that the liver, one of the systems that shifted most at menopause, sits at the centre of how the body handles both fats and glucose. And sleep, which got worse after menopause in this data, matters for glucose too; the research suggests a short or broken night can make the next day's responses to food noticeably bigger.
What a glucose monitor for wellness can show you
A continuous glucose monitor or CGM (we call them energy sensors) is a small sensor worn on the back of the arm that reads glucose every minute, usually for two weeks. A wellness CGM doesn't diagnose anything; blood tests do that, and anyone worried about their cholesterol, liver or bone health should speak to their GP. You also don't need diabetes to use one: in the UK, sensors are available for wellness use alongside coaching services like ours.
What a sensor can show is how your own body responds to the things you have some say over. The order you eat a meal in, a ten-minute walk after dinner, three short nights in a row, a strength session, a week of deadlines. Over a fortnight the patterns tend to become obvious, and they're specific to you rather than to the average woman in a dataset.
In midlife that feedback earns its keep, because so many of the habits that help work across several systems at once. Strength training supports bone, and muscle is where glucose from a meal can end up, so building and keeping it helps on two fronts. Better sleep helps mood and next-day glucose. Moving after meals is cheap and easy to test. None of these needs a sensor to be worthwhile, but seeing your own numbers respond is often what makes a habit stick.
Nico isn't a women-only platform, and the men in this study weren't standing still either. Their markers drifted upwards with age too, just without the step.
A note on HRT
Women in the study who were taking menopausal hormone therapy had noticeably smaller jumps, especially in bone, liver and kidney markers, so their results after menopause looked more like a smooth continuation of what came before. That's a striking result, but it comes from observational data. Women who choose or can access HRT may differ from those who don't in ways the researchers couldn't fully adjust for, and the authors say randomised trials are needed to confirm it. HRT was also linked to higher CRP, an inflammation marker, which earlier research ties to oral HRT rather than patches. Decisions about HRT belong with your GP or a menopause specialist.
Questions people ask
Can a glucose monitor tell me if I'm in perimenopause? No. A CGM measures glucose, and perimenopause is diagnosed from symptoms and, sometimes, hormone blood tests. What a sensor can do is show how your glucose responds to food, sleep and stress while your body is changing.
Does menopause raise blood sugar? In this study, fasting glucose and HbA1c rose gradually with age in both sexes, with no sudden jump at menopause. How glucose behaves across the day around menopause wasn't measured and is still an open question.
Do I need diabetes to use a continuous glucose monitor in the UK? No. Wellness CGMs are available to people without diabetes, usually as part of a coaching or tracking service. They're for understanding patterns, not for diagnosis or treatment. Nico uses CGMs as part of its programme
The decade before
The authors argue that their findings stretch the window for preventative care to almost ten years before menopause. For a woman in her late thirties, that window is open right now, and most of what happens inside it will never show up on a once-a-year fasting blood test.
Source: Pridham G, Hayut Y, Lavi-Shoseyov N, Neeman M, Hovav N, Toledano Y, Alon U. Population-scale reconstruction of menopause dynamics reveals a physiological cliff at the final menstrual period. Nature Medicine 32, 3823–3831 (2026). https://doi.org/10.1038/s41591-026-04614-0
Wear a sensor, log your breakfast, and your coach will tell you by lunchtime whether it worked.
This article is general information, not medical advice. If you're worried about your blood sugar, talk to your GP.
