I have PN that appears to worsen after a glucose load or that is due to hyperglycemia peaks (I'm prediabetic, 40 years old).
As many here, I've been trying to figure out what could be the cause of this thing, high blood sugar spikes are a likely suspect so I'm trying to find what things are good and bad to keep my blood glucose levels steady.
During the process of getting disciplined on watching what I eat, it dawned on me that lately I've been drinking a lot more coffee than I used to: switched to espresso, then to double espresso. A cup almost every day.
I didn't think much of it because I had heard that coffee drinking reduces the risk of type 2 diabetes.

But I found this paper today:
Lesley L Moisey, Sita Kacker, Andrea C Bickerton, Lindsay E Robinson and Terry E Graham. Caffeinated coffee consumption impairs blood glucose homeostasis in response to high and low glycemic index meals in healthy men. American Journal of Clinical Nutrition, Vol. 87, No. 5, 1254-1261, May 2008.
PMID: 18469247

The study went like this: subjects drank a cup of coffee, either decaf or regular (with a precise caffeine dose), and an hour later they were given a bowl of cereal with milk: either Crispex (with a high glycemic index, that is sugar reaches the circulation faster) or All Bran (low glycemic index, sugar gets in blood slower). The amount of cereal was calculated to provide the same carbohydrate content and the amount of milk was the same too.

This is the graph that shows the main finding of the study:
http://neurotalk.psychcentral.com/album.php?albumid=572

Basically, drinking regular coffee made blood sugar go higher and stay high for a longer time in comparison to decaf coffee. So that if you had regular coffee and a not-sugary breakfast cereal (i.e. All Bran) your sugar spike was the same or worse that if you had a sugary breakfast cereal after decaf coffee.

The full text is here
and an easier to read summary/comment here http://4abettalife.com/why-your-morn...aking-you-fat/

I'm thinking that epidemiological studies and results only go so far, people vary too much in their biological responses and studies take too long to get done.
It is not useful for me if *in general* coffee drinking reduces the life-long risk of diabetes. What I want to know is if drinking a double espresso almost every morning might have something to do with developing this PN and if giving up the espressos might help stop the ongoing damage.
I have a glucometer, right? So I'm going to record the effects of decaf and regular coffee in myself. It seems a pretty straightforward thing to do.
I'll keep you posted.

Well, medical stuff tends to be contradictory and confusing.

Here is a paper about the opposite effect:
So yes, if you have the testing supplies at home, test yourself.
See what happens, and do it more than once.
And please do let us know.