Caffeine, coffee and type 2 diabetes

A new study of caffeinated drinks and type 2 diabetes caught my eye. I’m always on the lookout for studies on coffee, because – let’s admit it – I love coffee, and like many other coffee aficionados, I fear that someday this adored pleasure will be found a guilty one. And then what shall we do? Decide it’s worth the risk? Or convince ourselves we never really cared for this delicious, thought brightening, history-defining drink?

For coffee lovers most research news has been reassuring. Years of investigation have shown that coffee in moderation poses no threat to healthy adults – those worries about heart disease and cancer risks end up being unwarranted. What’s more, the coffee habit has even been shown to confer health benefits, and is associated with protection from Alzheimer’s and Parkinson’s disease, stoke, gallstones and liver disease.

Caffeine and diabetes

The new study, published in the American Journal of Clinical Nutrition (online ahead of press), observed a very large population of about 75,000 women and 40,000 men for more than two decades, trying to see if there’s an association between the caffeinated and caffeine-free drinks they consume and the development of type 2 diabetes.

The study looked at all types of typically caffeinated drinks: coffee, tea, sugary drinks and artificially sweetened drinks.

Over the years more than 10,000 of the people developed type 2 diabetes. There are many factors known to increase the risk of developing type 2 diabetes, such as obesity, family history of diabetes, hypertension and smoking. After controlling for those, the researchers set about to see whether caffeinated drinks made a difference.

Here’s what they found:

• Coffee, caffeinated or decaf, was associated with a lower risk of type 2 diabetes.
• Caffeinated tea was associated with a lower risk of type 2 diabetes.
• Sugary drinks, both caffeinated and caffeine free, were associated with a significantly higher risk of type 2 diabetes.

Are coffee and tea protective?

It’s impossible to conclude cause and effect from these kinds of studies. The authors describe a few plausible protective mechanisms in which coffee and tea can affect diabetes: both are rich in flavonoid antioxidants, which may help in reducing inflammation. It’s likely that it’s one of the multitude of compounds in coffee and tea – or several of them acting together -- that have positive health effects, and caffeine, which we treasure for its stimulating properties, has nothing to do with the other benefits.

On the other hand, the association between sugary drinks and diabetes is very suggestive of a direct biologic effect:  sugar and high fructose corn syrup are quickly absorbed and cause spikes in blood sugar and insulin. Several studies have shown that sugary drinks are linked with diabetes independently of the weight gain associated with these drinks.

What this study shows quite well is that it’s the sugars that are associated with the development of type 2 diabetes, not the caffeine. The caffeine content of soda seems irrelevant to the risk of diabetes.

So hurray for coffee – and tea – but before you go on a coffee binge, a few words of caution: most studies showing coffee’s benefits and lack of harm looked at people drinking coffee in moderation. Coffee in moderation is fine, but that doesn’t mean that coffee in large amounts is even better – quite the opposite!

That also doesn’t mean that caffeinated drinks are healthy – it seems that energy drinks can be quite unsafe.

And it doesn't attest to caffeine’s safety for kids. These coffee and caffeine safety studies were done with adults only, and kids’ physiology is quite different.

Dr. Ayala

Image: The shrub on the right, Coffea Arabica, carries coffee berries. On the left: the familiar roasted coffee beans, which are the seeds of the plant.

Full disclosure: I’m vice president of product development for Herbal Water, where we make organic herb-infused waters that have zero calories and no sugar or artificial ingredients. I’m also a pediatrician and have been promoting good nutrition and healthy lifestyle for many years.