Updated 09 February 2017

High GI foods boost diabetes risk

People who eat a lot of low-fibre and processed foods that quickly spike blood sugars may, not surprisingly, have a significantly higher risk of the most common form of diabetes, according to a new study.

"By raising blood sugar and demanding that the pancreas keep pumping more insulin, meal after meal, day after day, a high-glycaemic diet can put people at risk of diabetes over the edge," said Dr David Ludwig, who studies obesity at Boston Children's Hospital but was not involved in the work.

How the study was done

The report analyses 24 studies published since 1997 that tracked what 125 000 adults ate. The new study confirms links prior researchers made between those so-called high-GI foods - including white bread and potatoes - and diabetes.

Published in the American Journal of Clinical Nutrition, the new report from researchers at the University of California, Los Angeles, Oxford University in the UK and others found that the 125 000 studied adults daily ate an average of 139 grams of sugar or its equivalent.

According to the US Centers for Disease Control and Prevention, about 8% of Americans have diabetes. More than 90% of those cases are type 2 diabetes, which prevents the body from properly using or producing the blood sugar-regulating hormone insulin.

Choosing the right foods for your diet

The analysis did not pinpoint precisely how many of the 125 000 participants actually developed the disease, but for every additional 100 grams of sugar per 2 000 daily kilojoules, people had a 45% higher risk of type 2 diabetes."It's easy to get more than 100 grams, especially if you're not being careful to choose the right kinds of foods," research dietician Heidi Silver, of Vanderbilt University Medical Center in Nashville, who was not involved in the new study.

Low-GI foods include fish, meat, high-fibre fruits and vegetables, nuts, cheeses and other dairy products, brown rice and other unrefined grains. The glycemic load is calculated by multiplying the total of carbohydrate grams in a given food by its assigned glycaemic index, a number that can be found in online tools.

Understanding high-glycemic and low-glycemic

It's important for the general public to better understand what high-GI and low-GI mean, researchers said, and how to figure out their glucose intake. A very ripe banana, for example, has far more grams of sugar than one that's still green. Eaten raw, rather than cooked, sweet potatoes have a low glycemic index.

There's a "jungle of information and misinformation out there," clinical dietician Kari Kooi of Methodist Hospital in Houston said. "For instance, fiber (in prepackaged energy) bars is not the same thing as natural fibre you get in fruits and vegetables," said Kooi, who was not involved in the current study. "That's deceptive to consumers, who also may not realise that just having fiber...doesn't necessarily mean the same thing as being low-glycaemic."


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