Blood Sugar & Covid-19

Part 1: The experiment begins

Today I want to talk about building immunity and in particular avoiding coronavirus by your controlling blood sugar.

I’ve taken an interest in sugar avoidance over the last few years. Some might say that it verges on an obsession. This has been followed by looking into the benefits of a low carb diet. I know that this is controversial and some clinicians don’t yet accept that this should be the cornerstone of management of pre-diabetes and type 2 diabetes. I feel confident that their views will change, as evidence builds of the numbers of people helped by this diet; some proponents believe that low carb eating is beneficial to most people. For people with or at risk of diabetes it is likely to improve their immunity to infection including to Coronavirus by keeping their blood sugars under good control.

Dr David Unwin (photo from

Fans of low carb eating include Dr David Unwin, who has gained the title of ‘the Low Carb GP’ and I was delighted to meet him a few months ago. He showed me charts that  reveal that different carb-rich foods raise the blood sugar much more than one might expect and that this includes even healthier options such as wholemeal bread. He said that the best way to properly get to grips with this is to monitor one’s own blood sugars for a fortnight. He recommended a Freestyle Libre device for this purpose.

I knew that this couldn’t be pain free and not surprisingly, I procrastinated. The self-testing went onto my to-do list and repeatedly got dropped to the bottom of the pile. I’d not seen the device but imagined something with multiple fine hair-like needles, attached to the skin of the upper arm. I am a bit of a coward. Also, buying a single device privately for just a fortnight costs nearly £50.

My friend, who takes insulin, had an old monitor available. (A more up-to-date smartphone than I possess would have worked too.) I bought the device (privately) and he attached it for me. It had only a single very fine needle and was otherwise a flat white disc, like a large draught counter, but not as thick. Putting it on was slightly sharp, but quite tolerable. It stayed well stuck to my upper arm and didn’t even hurt when I accidentally lay on it at night. The monitor was amazing. I had only to turn it on and hold it over my arm to get an instant blood sugar reading. I could do this as often as I wished, quite painlessly.

A few years ago, I’d decided that it would be really interesting and enlightening to analyse blood sugars for typical Jewish food such as a bagel, some kuchen and also challah. It didn’t happen but now I had an opportunity to personally experiment.


To assess the impact on blood sugar, I chose some foods which I love, and also several foods which I wouldn’t usually eat.  Many of the results were unsurprising. One would expect that a slice of cheesecake would send my blood sugar up. But remember that I don’t have diabetes. It isn’t long since I had a normal glycated Hb test at my GP surgery. (This is an estimation of whether your average blood sugar over the previous 3 months has been OK.) Whereas, for a ‘spot check’ you normally aim for a blood sugar below 7.8 taken 2 hours after a meal or under 8.5 if you have type 2 diabetes.

So, looking at the bagel etc: a single bagel with smoked salmon and cottage cheese, (I’d run out of the more normal cream cheese,) sent my blood sugar soaring to 8.4 within an hour. I dread to think how high it would have gone with 2 bagels (which used to be my usual lunch when out hiking). It isn’t just the white bread but also large amounts of sugar used in standard bagels which makes them delicious but not healthy. A glass of grape juice sent my sugar from 4.4 to 6.9 within just 40 minutes. It is not the healthy drink that many parents assume, when pouring it out in large quantities for their kids. It has 3.5 teaspoons of sugar per 100ml, although ‘light’ grape juice will be better. (Remember that a young child should have no more than 5 tsp sugar per day.)

Me and my kuchen

I had only a single but reasonably sized slice of iced kuchen, (like a bun loaf) with a thin layer of butter. I didn’t enjoy it, as it tasted cloyingly sweet now that I’ve weaned myself off sugary foods. For my troubles, I hit a blood sugar of 6.4 within just over an hour and my sugar stayed quite high for a further hour. Why on earth is buttered kuchen considered a suitable ‘treat’ for visitors? Usually a single slice is not considered to be enough by the hostess, so more concentrated sugar is foisted upon you!! Two slices of lightly-buttered challah sent my blood sugar shooting up to 7.9 and it stayed high for about an hour. You may have noticed that the bagel and challah caused higher sugars than the kuchen. All 3 have excessive added sugar. It is high time for Jewish shoppers to demand that bakers reduce the sugar-content in their products, or else make their own, using wholemeal flour and much less sugar. Ideally, they might cut down on bread altogether. Dr Unwin showed that even a slice of wholemeal bread can raise the blood sugar by as much as 3 teaspoons of sugar. (However, in general nutritional terms, the wholemeal bread is far superior to sugar).

blog chart
Results of my experiment

Far the worst was when I had a large fruit scone with a smear of jam. My blood sugar hit the heights of 12.6 after one hour. There will be more about this in my follow-up blog, but don’t worry, I’m fine now! I’ve just learned that most of us don’t tolerate a high intake of sugary and starchy foods. I can’t be complacent just because I’m skinny, especially during these times of the Corona virus, when it’s important to be as fit and ‘battle-ready’ as possible.

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