In their study, the researchers examined the longitudinal associations between changes in GL and the incidence of diabetes among pre-diabetic patients. According to them, only a few prospective studies evaluating the association between GL and diabetes have accounted for changes in GL. They believe that the diet of patients could be modified in response to an awareness of pre-diabetes. They hypothesized that subjects with low and high baseline GL would show different correlations with diabetes. (Related: New study looks at the anti-diabetes potential of autumn olive.)
To test their hypothesis, the researchers recruited a total of 493 pre-diabetic patients (142 men and 351 women) aged between 40 and 79. They obtained dietary records and conducted oral glucose tolerance tests on the pre-diabetics every year for four years. They also divided the participants into low- and high-GL groups based on baseline GL. During a median four years of follow-up, they reported a total of 108 incident cases of diabetes.
Among those with a high baseline GL, the incidence of diabetes increased as GL reduction decreased, and the multivariate-adjusted HR (95 percent CI) was 2.34 (1.27--4.29) when comparing the lowest to the highest tertiles. However, among those with a low baseline GL, the researchers observed no significant association. Regardless of baseline GL status, the incidence of diabetes was higher in patients with a high follow-up GL than in those with a low follow-up GL, and the multivariate-adjusted HR (95 percent CI) was 1.64 (1.09-2.45).
Based on their findings, the researchers concluded that GL reduction is associated with a lower diabetes risk in pre-diabetic patients with a high dietary GL, while in patients with pre-diabetes and a low dietary GL, further reductions in GL do not have any additional effects. Reducing dietary GL, therefore, can help pre-diabetics with a high GL prevent their symptoms from developing into full-blown diabetes.
When people eat foods rich in carbohydrates, their blood sugar levels go up. The extent it rises depends on the type of carbohydrates — the basis for glycemic index (GI) — and how much carbohydrates they consumed. The combination of both factors is represented by GL, which is computed as the value of [GI x carbohydrates (in grams) per portion] divided by 100. Determining GL is the best way of comparing the blood glucose values of different types and amounts of foods.
Although GL is very useful for scientific research, GI is the value that diabetics and overweight people often use. This is because a diet with a low GL may be full of healthy low GI carbohydrates but contain too much protein or unsaturated fats, such as those found in some discretionary foods. On the other hand, choosing low GI foods allows people to select low GL food anyway; hence, people with diabetes are recommended to and follow dietary interventions based on GI.
However, while assessing GI ensures that a diabetic's diet contains balanced amounts of carbohydrates, fats, and proteins, GL is still useful for determining which foods and portions are suitable for maintaining good blood sugar levels. GL can be particularly useful for patients that have specific meals quite often or if they are trying new meals and are unsure of how the foods may change their blood glucose levels.
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