Now, there's further evidence that coffee also helps cut the risk of developing type-2 diabetes. In the most recent meta-analysis, researchers found that drinking two or more cups of coffee per day was associated with a 12 percent decreased risk of developing the disease. And even decaffeinated coffee seemed to cut the risk, though not as much as the caffeinated kind.

Of course, the most significant risk factor for type-2 diabetes is weight. And, indeed, the study found that coffee's protective effect didn't seem to hold up as well in overweight people.

So, what explains coffee's beneficial effects on diabetes?

Well, researchers say there may be several explanations. Coffee contains a host of polyphenols, beneficial plant compounds. And researchers have identified one compound, chlorogenic acid (CGA), which has been shown in studies to delay the absorption of glucose.

But man cannot live on coffee alone. So what other foods may help decrease risk of type-2 diabetes — or help people manage the condition if they've already been diagnosed?

The American Diabetes Association has a list.

Not surprisingly, beans and leafy greens are at the top of the list. In addition to being a cheap source of protein, beans contain key nutrients such as potassium and magnesium, which has been shown to help regulate blood sugar.

Also on the list are citrus and berries, which are loaded with polyphenols and fiber.

Nuts, as we've reported, can help control appetites and also are a good source of magnesium.

Sweet potatoes make the list. Compared to white potatoes, sweet potatoes contain lots of vitamin A and fiber.

All of the foods on the list, according to the ADA, have a relatively low glycemic index, meaning they help prevent spikes in blood sugar.

Copyright 2013 NPR.

Alzheimer's diseaseAlzheimer's disease

How Coffee, Citrus And Nuts Help Cut The Risk Of Diabetes