Does caffeine raise your blood glucose?

Hi everyone,

I know that caffeine consumption can raise blood glucose levels for some people. Does anyone else out there experience this? Anyone taking extra insulin for it, and if so - how much?

I have found recently that for a few shots of espresso (mixed with water, none of that froo froo latte stuff) I am bolusing the equivalent of 30 grams of carb.

Any advice on how to calculate this? I would love to know what other folks are doing if they experience this.


for me (i run a coffee shop) it depends on the time of day, the stress levels, and all of that other stuff. it is so unpredictable that i can only correct after the fact. the reason that caffeine raises bs is because of its effects on hormones and adrenaline. that stuff kicks around in differing levels… so its effects are differing as well

I answered a question about this last week:

I don’t know precisely how much caffeine affects my blood sugar, but it certainly affects my ability to sleep, so I try to stick to one cup of coffee a day. I do believe it raises my sugar, though. There have been many mornings when my sugar shoots up to 15 mmol/l (270 mg/dl) or so after just a small bowl of cereal (15 g of carb) and a coffee. It pisses me off.

I am a huge energy drink addict, and found out my sugar only shoots up when I drink them with meals.

Caffeine runs in my blood, in average I drink 4 to 6 cups of black coffee a day. Don’t believe it effect my BG level. I never bolus for it! I drink it with nothing added just water and pure dark coffee (light roasted if it differ!)

When I went for training on my pump in April of 2008, the CDE mentioned this issue. I’ve been diabetic since 1979, and this was the first I had heard of that. So, I started closely watching my blood sugars after my huge morning cup of coffee, and sure enough, it was spiking me. I find bolusing for 10g works for me. Although in the past month, I’ve started exercising after my coffee but before my breakfast. I skip the coffee bolus and let the walk on the treadmill take care of the coffee spike. :slight_smile:

I have never bolused for caffeine, and I drink a lot of coffee. Its important to remember too that often folks drink coffee first thing in the morning when lots of hormones that help your body “wake up and get going” (adrenaline, cortisol, etc) are also being activated, and that can raise your BGs. If I wake up low first thing in the morning, I often don’t need to eat anything to correct it, as soon as I start getting up and getting moving, my BG comes up on its own. It may be that when you drink the coffee there are other hormones at work, raising your BG. A good experiment would be to test drinking caffeine at different times during the day and see if you always need to bolus. Interstesting!

my son george drinks a lot of diet coke and his blood glucose levels are okay …janet x

I wear a sensor .I drink black coffee 1 cup for breakfast ; estimate my breakfast carbs at 77 grams …so do not really have prove , that caf. will raise my BG , also do my morning walk . In the afternoon I get a cappucino with 1 percent milk, no added flavours , est. 14 grams of carbs …I always noticed a rise in BG …read on TU some time ago , that caffeine raises BG …and I started to order DECAF …I am a happier camper, read coffee drinker , numbers staying flatter . I stay away too from regular diet coke in the afternoon as well …only decaf, diet for me . Cannot advise you how many grams of carb you would need to bolus for …but 30 grams sounds like a lot .

drink black coffee it dont rase blood sugar

Similar experience. Had never heard the theory that caff can raise your sugar until this year.

My CDE suggested a theory that, in her experience, it’s very individual. She says she notices even that type A personalities seem to need the bolus for the coffee more often than type B personalities (go figure - maybe we just get too excited about getting that caffeine boost!). My CGM tells me that my BG rises about 30 mg/dL after my morning cup. I had no idea. I thought that the small amount of sugar-free creamer and the caffeine would have a negligible effect, but I think she was right. She suggested I bolus half a unit to a unit for my morning cup and see if it helped. It has been working very well for me for the last couple months, but I doubt I would have noticed it on my own.

If my beloved Diet Coke starts increasing my blood glucose, I quit! That’s my only vice left :slight_smile:

Starbucks has a nutrition sheet in any of their outlets. I use their carb guide when I have my latte in the morning (though I make it myself at home)

No problems here. I’ve not really noticed any difference with BG levels after coffee. I don’t drink a ton, but do drink on a totally regular basis, (this sounds like some sort of AA confession or something) but yeah, no issues with coffee/caffeine.

My b/g sometimes spikes wildly after a cup of coffee. I think it indeed does have something to with with the amount of stress/adrenaline/etc in your system. I know in the morning before a race I can wake up at 90 b/g and eat a hardboiled egg and a cup of coffee and then an hour later my b/g will be at 200 – I’m hoping its all just do to nerves. I’ve also found if I treat the high with my usual ratio dose I’ll go too low.

Hope you got it figured out!

I drink lots of diet Coke with no need to bolus. Coffee on the other hand, I need to bolus for particularly in the morning about a half of unit, mid morning same and usually don’t have to bolus if I happen to drink in the evening depending on my BG.

Yes, caffeine in coffee raises mine, but diet soda's I haven't noticed.

I think it's more of the morning hormone thing for me.

I don't usually bolus for it, since it just sort of gets included in my breakfast bolus.

One thing I HAVE noted though is that when I am doing coffee at home on weekends, which is freshly ground very dark roast beans and several very strong cups of coffee, seems to raise it more than the weaker weekday office coffee.

I have similar experiences, though the weird thing it for me it can take me higher or lower!!! In case I go higher it has an effect of 20-30gr carbs, in case I go lower it is much more like I am going into a hypo!!! Hence I always add a bit of milk, just to be on the safe side and bolus afterwards in case I am to high.

My blood sugar goes up after coffee, and then a couple of hours later it drops like a rock. When I drink coffee (about one cup per day) I take a half normal bolus when I drink coffee to keep it near normal. Otherwise I fall quickly.

rick phillips

1 Like

I have been checking my blood glucoses an hour or so after drinking my standard two cups of “half and half” (half caffeine, half decaffeinated) and I have observed an increase in blood glucoses by about 20-30 mg. This follows a normal blood glucose first thing in the morning. I agree with some of you that it may be a “morning and awakening” hormone effect that is working. I also have read that caffeine stimulates the liver to produce any stored glucose it may have. Finally, I do NOT notice glucose increase when I drink my coffee with breakfast and take my bolus. I too will not give up my morning coffee :-).