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Does insulin timing really make a difference?

I’ve been thinking a lot about insulin timing lately… Which might seem like a weird comment to make, except that this year – at last, finally, thank heavens – ultra rapid-acting insulin is coming to South Africa.

Let’s talk about insulin timing

When I was diagnosed with Type 1 diabetes 14 years ago, I was told to inject as I sat down to eat. Which I did, for many years, until I started wearing a flash glucose monitor and saw the blood glucose spikes every time I did that. I’ve now learnt to inject at least 20 minutes before I eat.

What I find so fascinating about things like insulin timing is that we are literally all different. When we asked our community if they inject as they eat or 15-30 minutes before, we got pretty much every response under the sun.

Some people inject 15 mins before, some 30 minutes before, some as they eat, some just after they eat, some 30 mins after they eat. And for so many reasons, right? Blood glucose reading at the time, type of insulin, speed of eating…

Farzana said she injects just before she eats, because you don’t know when you’re going to eat exactly. And the worst is when you inject and don’t eat within the 15 min time frame.

Aaron said after eating, because you never know if you’re going to finish the food, which is a good point. Lesinda said the same thing – she only injects after she’s dished her plate, because she’s not sure what she’s going to eat.

Elre’s was my favourite comment – she said she tries injecting before she eats, but sometimes she’s just too damn hungry to wait!

I askedSane Mazibuko, who was diagnosed with Type 1 diabetes 25 years ago, about insulin timing because she has literally lived through it all.

First off, 25 years is extraordinary. What has changed in the world of insulin since you were diagnosed?

 A lot has definitely changed. I’ve also seen a lot of different insulin types being introduced, as opposed to what was available then. And also I can safely say that there’s been a lot of research done into insulin and how our bodies react to insulin.

Was insulin timing ever explained to you?

No! It was not explained. I knew that I would have to take my insulin 30 minutes before eating but I was never told why.

What’s the most frustrating part about having to time your insulin injections, for you?

I think it’s understanding what I’m about to eat, and what insulin I need to take . So for example, taking six units today to have fish and a salad. But also that does not mean that I must take six units to have for example pap and my favorite stew, that’s a different insulin amount.

“For me, the most frustrating thing about insulin timing is that it changes every day! It depends on the time of day, what I’m eating, how much exercise I’ve done, what my blood glucose is as I’m about to eat… it’s like a super complex mathematical sum.”

Sane Mazibuko, living with Type 1 diabetes

I thought we could try and get some clarity on the issue by chatting to endocrinologist Prof. David Segal.

What is actually going on with insulin timing?

So first of all, we need to understand how insulin actually works and that we are injecting non physiological products. So we’re injecting insulin that’s been modified or highly modified under your skin in a place that isn’t your pancreas and isn’t getting to your liver fast enough. So it has to be absorbed from under the skin and the absorption characteristics of insulin change from injection to injection actually, even with the same product.

There’s a variability in how that insulin gets absorbed from under your skin into your bloodstream and then distributed to where it really needs to be – which is peripheral tissues and liver and pancreas. And I think that creates a lot of variability that people aren’t aware of that’s just built into the product.

Don’t expect the same response every single time you inject.

Prof. David Segal

Insulin absorption is also a factor

So that’s problem one. Problem two, is that it does take time for those molecules, or the insulin molecules under the skin to be absorbed into the bloodstream. And that can take anywhere from 0 to 30 minutes. But if you look at the clinical trials, it takes 15 to 30 minutes, for instance, to start appearing in your bloodstream after an injection. But its peak glucose lowering effect happens later, which is only at about 60 to 90 minutes.

So that means that if you eating highly processed foods or carbs, they’re going to get into your bloodstream faster than your insulin can meet it.

Do you have any suggestions or magic tips on how to make it less frustrating?

So I think the most important thing to understand that instant timing is very, very important.

If you want to control your after-meal blood sugar spike, you have to get the timing right.

Prof. David Segal

There are other things that influence your after-meal blood sugar spike. But if you don’t understand the timing and other factors you work on the only other thing you get to play with, which is dose. And the dose does not dictate your after-meal blood sugar.

I am very excited about ultra-rapid-acting insulin coming to South Africa this year. Does this mean we’ll be able to inject as we sit down to eat?

Yes, I think so. It’s one less thing to think about. There are just too many factors to consider: I’m hungry, I don’t have time, I forgot, it’s now too late. Now, what do I do?

Living with diabetes and doing diabetes behaviours is inconvenient, at the best of times, and having to do it multiple times a day, because we eat multiple times a day, it’s a nightmare.

The convenience of being able to inject a much faster acting insulin that starts working quicker, reaches its peak quicker and gets out of your system quicker. That’s exactly what we want.

Prof. David Segal

Would you rather listen to this information?

Here’s an episode of our podcast about it!

About the podcast guests

Sane Mazibuko is a 32-year-old from KZN who now lives in Cape Town. She was diagnosed with Type 1 diabetes when she was 7 years old.

Sane is an HR professional who enjoys navigating life with her 2-year-old daughter. She is currently trying to get back into shape while doing her bit to share her experiences with other diabetic people and learn from them as well.

Follow her on Instagram: @thesanediabetic

Prof. David Segal is a paediatric endocrine and diabetes specialist. He was appointed as an Honorary Adjunct Professor in the department of Paediatrics at the University of the Witwatersrand and was a co-founder and chief medical officer of Guidepost, an eHealth company delivering diabetes coaching services nationally. His current interest lies in using systems thinking and technology to reshape the health care system by empowering the patient to become an active consumer and customer.

Find out more at:

Photos by Nathan Dumlao and Diana Polekhina on Unsplash

What to read next?

How to interpret your glucose reports: highlights from a Masterclass with endocrinologist Prof. David Segal.

SMART goals: what they are and why you need them.

The Type 1 diabetes toolkit: what you need to carry at all times

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Sweet Life is a registered NPO/PBO (220-984) with a single goal: to improve diabetes in South Africa. We are funded by sponsorships and donations from aligned companies and organisations who believe in our work. We only share information that we believe benefits our community. While some of this information is linked to specific brands, it is not an official endorsement of that brand. We believe in empowering people with diabetes to make the best decisions they can, to live a healthy, happy life with diabetes.