Blood Sugar – It’s Complicated

Cake CM

As a diabetes researcher I have a particularly keen interest in blood sugar (or blood glucose). If you have type 1 diabetes and need insulin injections, then knowing and understanding your blood glucose is pretty key to getting through the day (and night). But how worried should we all be about the immediate effect of different foods (and drinks) on our blood glucose?

Following the usual rules of nutrition there is a fair amount of advice out there; blogs teaching you how to stabilise the “peaks and troughs”; pitching slow-release energy foodstuffs against warnings of those that will cause you to come crashing down with a thump. To clarify, I’m not suggesting there is nothing in this – our bodies tend to put a lot of effort into keeping things the same, a repeated challenge to our system may cause damage over time.

Although we may notice a difference in mood and energy while our blood glucose fluctuates, if your pancreas is functioning properly, these fluctuations are unlikely to do you any immediate harm. It is different in type 1 diabetes when the pancreas is not behaving as it should, as these highs and lows can really put someone in danger. But the dip in energy you feel at your desk in the afternoon (possibly a blood sugar dip… possibly just tiredness!) is in no way comparable to a diabetic hypoglycaemic event which can cause panic, anxiety, palpitations, and carries a risk of losing consciousness.  

At the moment, we don’t really know for sure just how damaging the long-term effect of (non-diabetic) blood glucose variability is – there is a lot of debate in the scientific literature. It is the focus of much research, including our own, so I’m not trying to dismiss it by any means, but there are a couple of things to consider before changing your diet to follow the blood glucose trends. Maybe continuous ups and downs do put an extra strain on our bodies. Maybe this causes our cellular communication pathways to eventually breakdown and maybe this contributes to the development of type 2 diabetes. Or maybe the peaks and troughs don’t matter one bit providing the levels even out (on the lower end of the scale) in the end. Maybe, just maybe, that’s a few too many maybes to make a snappy stabilising story to sell…

One thing we can be fairly certain of is that everyone is pretty individual and our blood glucose response to a particular food is often not even the same every time we eat or drink it. Take coffee; for some people coffee seems to have no effect on blood glucose, for others it has been shown to cause a rise. In a recent experiment, we found that black coffee (no sugar), consumed at the same time, before any other food or drink that day, caused an increase in the blood glucose of one participant, but that increase was markedly different on each day. Most likely because the participant did not do exactly the same thing on any of the previous days – food, exercise, alcohol – so chances are this caused a knock-on effect in the morning. So, we know that blood glucose variability is individual, and variable!

And where does this leave us? Does it mean blood glucose variability has no importance? Maybe not. I’m ticking the “it’s complicated” box for now. There is no simple answer. But what does it mean for your food choices? I am a believer in the holistic nature of a “healthy diet”, where mental health is as important as physical. Food has the power to give so much pleasure, pretending otherwise is not going to help keep the relationship healthy. Of course too much sugar is not good for us, that’s kinda the definition of “too much” after all…

We need to find our own individual balance; somewhere between cake every day for breakfast and a flat-out ban on any cake-related happiness. I know we’re all different, but cake is definitely good for my soul.


Claire is a Senior Lecturer in Biology at the University of Brighton; she has been a diabetes researcher for over 13 years. She is currently involved in research which uses continuous glucose monitors to understand glucose responses to food, drink and exercise. The project is also investigating the effect that variable glucose has on cell viability in the lab. In her spare time she enjoys researching the effect of cake, cheese and exercise on her own happiness.