Low GI Diets And Diabetes Risk

The Glycemic Index (GI) measures the impact a particular food has on an individuals blood glucose levels. GI is defined as the area under the two-hour blood glucose response curve after consuming a fixed portion of a particular food. A high GI value indicates that consumption of a particular food increases blood glucose levels both faster and to a higher peak than a low GI food.

Foods with a high GI have been linked to health problems with several scientific studies showing a link between high-GI foods and diseases such as coronary heart disease and type-2 diabetes. Furthermore, those who consume low-GI foods tend to have a lower body mass index (BMI) and lower overall fat levels which further reduces the likelihood of developing diabetes.

Diabetics are recommended to base the majority of their diet around low GI foods to avoid dangerous spikes in blood glucose levels and reduce the need for insulin. An Australian study involving 356 subjects found that diabetics fed a low-GI diet were better able to control their diabetes than those on the high-GI diet. They concluded “Choosing low-GI foods in place of conventional or high-GI foods has a small but clinically useful effect on medium-term glycemic control in patients with diabetes.”

The GI index uses glucose as a “base” measurement assigning it a value of 100. High GI foods are those with a GI value greater than 70 while low GI foods have a GI value lower than 55. Interestingly sucrose (more commonly known as table sugar), has only a moderate GI value and in-fact has less of an impact on blood sugar levels than foods such as white rice and baked potato.

Foods with a high GI index include dried dates (which actually have a glycemic index greater than 100), parsnips, baked potato, white rice, white bread, pancakes, watermelon, pretzels, and cornflakes.

Foods with a low GI include most fruits, especially those high in fructose (fructose has a GI of just 23), this includes pears, apples, plums, cherries and grapefruit. Most dairy products have a low GI because lactose (milk sugar), has a GI of just 46, the exception to this is ice-cream which has a moderate GI. Most vegetables, with the exception of potatoes, sweetcorn, pumpkin, and parsnips have a low GI. In general, fiber rich foods have a lower GI because fiber slows down the release of sugars into the blood stream.

An alternative measurement of a food’s effect on blood sugar is the glycemic load. While the glycemic index only tells us how rapidly a particular carbohydrate is turned into glucose, the glycemic index takes into account how much carbohydrate is in that serving of food. So for example Watermelon, which is mainly water, contains just 5% carbohydrate so while it has a GI of 72, it only has a glycemic load of 72 * 5% = 3.6.