Perimenopause & diabetes: what's really happening to your blood sugar

I've been living with type 1 diabetes for 23 years. Around 39–40, I started noticing I was getting more insulin resistant — it was harder to manage my normal food. I usually make a cup of coffee in the morning with soya milk, about 4g of carbs per cup. My blood sugar started climbing to 18 mmol/l — ridiculously high for such a tiny amount of carbs.

At the gym I noticed the same pattern: my sugar stayed high throughout training and climbed even more afterwards — partly explained by the nature of resistance training, which can raise blood glucose. But getting it back into range became a real challenge. My body simply wasn't reacting the way it used to.

I asked my diabetes team at St Barts in London what was happening. Of course I knew I was getting older, but nobody was talking about what that actually looks like in practice. They looked at my readings and said: all good, you're being too hard on yourself. But I knew exactly what it took to reach that “good” — so much more effort than before.

The medical gap nobody talks about

On work trips I had to skip meals because I couldn't risk eating something that would push me into very high blood sugars in the middle of a conference. I was starving to stay in range — constantly exhausted and hungry. Any emotion, good or bad, would send my blood sugar shooting up to 17–18 mmol/l, and I'd struggle to bring it back down.

At my next appointment I tried to raise this with my endocrinologist, but he said they don't have any training on women's health in this period of life. Because I still had regular periods, he told me I wasn't in perimenopause and didn't need anything fixing. When I brought up gaining belly fat, he said my weight was the same as last year — nothing to worry about.

I was left fighting alone.

Getting HRT prescribed was its own battle. My GP wasn't convinced that hormones affect insulin sensitivity — something so fundamental I assumed any provider would know it, given that all hormones affect each other. I'm grateful for the specialists who listened and prescribed HRT even though I still had regular cycles and no hot flushes. It changed everything. I got back a few years in my management — things were still a little harder and less predictable than before, but nowhere near as hard.

I have experience reading research papers and writing health and fitness news, so I decided to start an open conversation for women who are looking for answers, just like me.

Why blood sugar gets harder to manage in perimenopause

I recently changed my diabetes team and felt understood immediately — but even they pointed to the lack of research and information on women's health over 40 for those living with diabetes.

As oestrogen fluctuates and falls, insulin sensitivity drops. The same meals that used to keep your blood sugar steady can push it much higher, and it tends to climb more easily overall. I also noticed a pattern within my own cycles — one month would feel relatively normal and predictable, and the next my body simply wasn't producing as many hormones and I'd be far less sensitive to insulin.

This isn't a failure of your management. It's biology that the medical world is only beginning to take seriously.

What can actually help

HRT was the single biggest lever for me. If you're approaching 40 and finding your control inexplicably harder, it's worth having the conversation with a specialist who understands both hormonal health and diabetes — even if you still have regular periods and no hot flushes.

Resistance training is one of the most reliable tools for blood glucose management: building muscle improves how your body handles glucose, protects your bones, and steadies energy far better than any single supplement. That said, with sleep disruption, joint pain and blood sugar swings, even training becomes harder during perimenopause. I noticed this too. It doesn't mean stop — it means adjust.

Every decision about your management should be made together with your doctor. My goal here is to make sure you know what you might face, and what can help, so you walk into those appointments informed.

UK resources worth knowing about

If you're looking for somewhere to start, these two UK organisations have the most relevant information specifically for women with diabetes going through perimenopause.

What the research says

The medical gap is real — and only recently starting to be acknowledged in the literature. Here's where the evidence currently stands.

Lena Filatova

Lena Filatova has lived with type 1 diabetes for 23 years. She writes about women's health, perimenopause and diabetes management at lenafilatova.co.uk.