AYADoctor? Conflicting Diabetes and Coffee studies? (complex question, just WAG it)

Factual Questions
1

As you may know, the Harvard School of Public Health recently released a study that found men who drink 6 cups of coffee per day have a 50% lower risk of developing Type II Diabetes over men who don’t.

This story, from The Healthy Eating Club, cites two studies which (I may be reading this wrong) seem to suggest but not conclude the following:

Impaired insulin action is the key step in the development of adult-onset diabetes. Impaired insulin means the pancreas is forced to secrete more insulin to have the same effect till at some point the pancreas starts to fail, leading to the death of insulin producing cells.

Conflicting the Harvard report (possibly) are these World Health Organization statistics which show Italy has an extremely high rate of diabetes and according to common knowledge (and statistics) they also drink a whole bunch of coffee.

As you can see, all of this information is very conflicting and I am just wondering if someone could give me their WAG either in layman or scientific terms.

2

My second cite from the Healthy Eating Club is in the context of coffee being the cause of impaired insulin action.

3

The biggest predictor of whether you will get type 2 diabetes is genetics.
After that comes weight and fat distribution, blood pressure and blood lipids (cholesterol), smoking, drinking and exercise.

Unless the coffee drinkers and non-coffee drinkers were matched exactly for family history, weight, bp and cholesterol, diet and lifestyle the study is meaningless.

If you feel that you are at risk from type 2 diabetes, take more exercise, lose weight, reduce your alcohol intake, stop smoking and consider lipid lowering and blood pressure medications if necessary.

Those steps are all shown to reduce the risk factors for cardio vascular disease, diabetes and stroke.

THEN you can think about how much coffee you drink.

4

I think it’s worth noting that the two studies cited on the Healthy Eating page gave single doses of pure caffeine, then measured lab values. The Harvard SPH study observed the real-world effects of coffee, a complex mixture, over years. Though the Healthy Eating article was titled ‘Coffee’, it was actually about caffeine; e.g. “…the proliferation of caffeine containing soft drinks and food products, all of which are easily accessed by children, more research is needed…”

The Healthy Eating article misspelled the authors and didn’t provide a proper cite, making it hard to located the studies, but I believe they are speaking of this article and this one

The positive effect might come from other chemicals and effects. In fact, part of the effect probably does, since decaffienated coffee still showed a (weaker) benefit. Chlorogenic acid (an antioxidant that helps give coffee its flavor) was one candidate mentioned.

[However, the antioxidant effect of chlorogenic acid is probably irrelevant. The media likes easy labels: “antioxidants are good” and if a “good” effect is found, they want to attribute it to some “good” property, even if there is no clear link. Similarly “caffiene is bad, so coffee must be bad, as proven by studies that caffiene is bad!” – this study illustrates the circularity of that reasoning]

Comparing two separate Italian figures tells us little, and can be misleading. Italians speak Italian - maybe Romance languages cause diabetes? Maybe gene prevalence has a role? Or (here’s a shocker) maybe the many carbohydrate-heavy regional Italian diets may affect a carbohydrate storage and metabolism disease like diabetes? In fact, coffee is said to delay or lower the incidence of diabetes, suggesting that it may primarily act on those who would otherwise be predisposed. No one said it cured or prevented diabetes outright (e.g. Vit C and scurvy)

Besides, we shouldn’t be surprised to find that something that helps prevent a disease, turns out to be harmful in the disease itself. Running marathons may help defer or decrease the eventual severity of cardiovascular disease, but if you already have severe cardiovascular disease, a marathon can kill you. In a pre-diabetic, a regular fasting blood glucose of 60 supports a good prognosis, but in a diabetic, it’s actually a bit worrisome. [Hypoglycemia can kill, and diabetics have poor glycemic control. They might oversleep after a night of dancing, and forget to wake up]

The endocrinology of diabetes is complex. I’m not ambitious enough to attempt a full discussion, even without putting caffeine in the picture. This two year old editorial in Diabetes Care on caffeine and insulin is a bit long (4 pages), but it’s a good start on the then-state of the art