I have drunk caffeinated coffee every morning for the past 45+ years.
It doesn’t cause me either insulin resistance or glucose dumps, as that’s already happened prior to my ingesting any coffee (feet to floor syndrome).
I also drink copious quantities of Diet Coke (caffeinated) throughout the day.
I admit it - I’m hopelessly addicted to caffeine 
I did my own little mini experiment over about a month period: Black coffee vs coffee w/ almond milk. (I bolus 1U Humalog before getting out of bed to cover both DP and morning coffee. I don’t eat breakfast.) I spike way more from black coffee alone. (of course, we are all different!)
Here is my rationale, and for me, it works: When you wake up and start moving around, the liver can react by releasing glucagon in response to the fasting state your body is in. So, I “break” that fast by giving my body what it is craving: glucose. I start the day with one teaspoon (measured, always) of honey in my coffee. I love cream in my coffee, and that helps lower the glycemic load. Also, to be clear, I do bolus for the honey. In fact, I usually pre-bolus at least 15 minutes.
To be fair, any food high in sugar will work, such as juice, a cookie or small piece of pastry, but I decided on raw, local honey because it is an unprocessed food and can offer some health benefits, such as lessening of allergy symptoms. And if you’re a person who can roll out of bed and eat breakfast right away, I suppose that would work as well.
My philosophy, and it may not be a good one, is whatever works.
Karin7 and others: I did my experiment this week and indeed 2 extra units of Novolog at breakfast does the trick. See before and after BG pics, attached. I also used some cream another day and that also keeps BG down! A friend of my daughter suggested mixing coconut oil into the coffee and that does the trick also with a healthier fat and the flavor is hardly different from black coffee! (Trader Joe’s Triple filtered Coconut Oil is what I am using.
coffee is a killer for me in the morning and I drink decaf. I know it’s boring, but water in the morning hydrates you after not drinking all night.
Coffee not matter what or how I drank it spiked my blood sugar 100 % of the time. Caffeine, decaf, cream, no cream, no sweetener. I reluctantly gave it up and used dandy blend which is a wonderful replacement. No calories, caffeine and is not acid forming. I would get similar spikes and actually use coffee to treat lows cause it didn’t have calories. Giving insulin to simply drink coffee… nope just not worth it to me. Plus I would imagine you would get a low 3-4 hours later depending on your long acting routine.
My dandy blend recipe
1/2 - 1 TBS Dandy
8 - 12 oz unsweetened almond milk
Liquid stevia to taste
Dash of vanilla(optional)
Pinch of sea salt
Drink hot or cold. (can buy from amazon)
Here is a great video by a well-spoken PhD covering some of the studies. I believe it is the liver hormone reaction which raises the blood sugar. However, research shows that coffee does NOT cause insulin resistance.
" How Coffee Affects Your Blood Sugar, Insulin Resistance, and Diabetes Risk"
It raises my blood sugar, but I’m also a person who has to bolus for protein every time, so I’m weird. I’d be curious to see if people notice the same with coffee marinades.
just 1 cup of normal (1 - 2 teaspoons of coffee) has no effect on my sugar levels, but I also use unsweetened almond milk… if I use normal low fat or full cream milk then it will go a bit high.
The interesting thing I’ve found with coffee is that it’s actually helped bring down my sugar levels when I’m too high, but then I drink it with about 5 heaped teaspoons and very little almond milk and that helps brings my sugar levels down (much faster than fast acting insulin), when they are persistently high and fast acting insulin is battling to bring it down to a normal level. I have no idea how that works, but it’s been a great help for those specific occassions.
Those are helpful insights! I see my BG rise when using half/half vs cream but now I will try unsweetened almond milk!
Sounds like you are using instant coffee and I just purchsased some. I guess brewed coffee could be very different in amounts.
yes I use instant coffee and I usually go for one of the stronger blends. What I have found is that the stronger coffee beans give better results with sugar levels. Like there are some coffees that are made with chicory or lower mixes of coffee beans and then my sugar levels can sometimes go a bit higher. So I always stick to 100% coffee beans, something like arabica or robusta beans content and that works perfectly.
I would definitely suggest giving unsweetened almond milk a try, one thing just to be aware of… well for me at least, whenever I go back to using the unsweetened almond milk from normal milk (cause this almond milk is quite expensive here so I’m not always able to use it), but then there’s a bit of transition period where it takes a couple weeks to see the change in how my sugar levels don’t rise and stay at good levels, which might sound weird but just how it’s worked for me, so give it a good trial run before making the final call 
I teach yoga and use coffee to give a slight spike to sugar when I feel myself dropping. I only use almond milk unsweetened with liquid stevia but it will provide an artificial spike for me to finish class without dropping any lower. It will typically come back down shortly after class. So for me coffee will elevate sugar and has been my tool for saving my lows without over treating them.
