& making healthy choices easy A newsletter from the Glycemic Index Foundation explaining the benefi ts of low GI and the GI Symbol Program September 2012

The GI was originally developed to improve exchanges so that they more accurately refl ected the true physiological effect of foods on postprandial glycemia. It challenged a long-standing belief that sugars should be avoided in favour of starches. Evidence in support of low GI diets in is substantial and it continues to grow. Evidence supporting the potential of healthy low GI diets to prevent and reduce the risk of is also increasing rapidly.

Improved sensitivity and Weight loss Specifi c benefi ts of a low GI reduced Low GI diets also lead to greater weight in diabetes Low GI diets increase insulin sensitivity loss compared to other healthy diets7. in type 2 diabetes2 and have the added In a weight loss study where patients Improved glycemic control benefi t of reducing hyperinsulinaemia, with type 2 diabetes were randomised A healthy low GI diet will improve thereby preserving ß-cell function. to a low fat, high carbohydrate vegan glycemic control compared to a high In contrast, high GI and GL diets are diet, or a conventional diet following GI diet or a measured carbohydrate associated with an increased risk of American Dietetic Association exchange diet. A systematic review insulin resistance3 and the metabolic recommendations, the dietary GI and meta-analysis1 including 12 syndrome4. was associated with weight loss8. GI, randomised controlled trials lasting which was lowest in the vegan group, between 4 wks and 12 months (3 Reduced risk of vascular disease predicted changes in weight, where trials in type 1, 8 trials in type 2 and Randomised controlled trials (RCTs) every percentage point decrease in 1 trial in both) showed that low GI show that a low GI diet is associated GI lead to a 0.2kg weight reduction. dietsWhat compared is the to highGlycemic GI diets with improved lipid profi les, specifi cally Furthermore, weight loss itself reduceIndex? markers of glycemic control. higher serum HDL-C and reduced predicted reductions in HbA1c. These HbA1c levels were reduced by 0.4% LDL-C5. Low GI diets also signifi cantly improvements were independent of The Glycemic Index (GI) is the scientifically proven way changes in total carbohydrate and fi bre. pointsof ranking (95% , CI -0.7 tolike breads-0.2; andp<0.001) cereals, rice reduce concentrations of the similarand pasta, to fruit,the starchy reduction vegetables seen and , with oral and infl ammatory marker, C-reactive milk and yoghurt according to how they affect your 6 hypoglycaemicblood glucose (sugar) agents. levels. protein (CRP) . Most people don’t eat too much carbohydrate. In fact, most people just eat the wrong kind of carbohydrate. And that’s where GI comes in: The Glycemic Index (GI) is a relative To make healthy choices easier we Not all carbohydrates are created equal GLYCEMIC ranking of carbohydrate in foods developed the GI Symbol Program, Carbohydrates with a low GI (55 or less) will make your blood glucose rise slowly and fall gently over a longer according to how they affect blood a not-for-profi t health initiative time. Carbohydrates with a high GI (70 or more) are glucose levels. Foods with a low GI backed by the University of Sydney digestedINDEX quickly causing your blood glucose levels to spike and then crash. (GI ≤ 55) release glucose into the and Juvenile Diabetes Research bloodstream at a slow sustainable Foundation. The GI Symbol is a rate, and have proven benefi ts powerful tool for quickly and reliably for health. making healthy food choices when grocery shopping. It’s your guarantee A low GI diet is not a but a that the GI value stated near the way of eating that is sustainable in information label is accurate the long term and is backed by over and that the food meets strict 30 years of scientifi c evidence. This nutritional criteria. includes facilitating the management of diabetes, weight loss and weight The free monthly GI Newsletter loss maintenance and reducing the informs you of the most recent fi ndings risk of developing type 2 diabetes, from around the world (Register at diabetes complications and other http://ginews.blogspot.com)

Research has shown that we eat too many high GI chronic lifestyle diseases. foods and not enough low GI foods. The bottom line is that the average GI of our diet is often too high, putting us at risk of developing significant health problems.

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1000_HA_GI_HealthyChoices_FA02.indd 3 24/04/12 4:39 PM GI in Low GI diets improve glycaemic control in children and adults with Type 1 diabetes and are now recommended as a part of type 1 diabetes education9. By using a continuous glucose monitoring system (CGMS) to measure the blood glucose profi les in people with type 1 diabetes eating macronutrient-matched low- and high-GI , researchers observed signifi cantly lower daytime blood glucose when low GI meals were consumed10.

The Eurodiab Complications study investigated the dietary intakes of 2810 people with type 1 diabetes and found that those with the lowest HbA1c levels had the lowest dietary GI11.

Lower blood glucose excursions expected with a low GI diet has led researchers to explore the optimal pattern of insulin delivery for low-GI meals. A dual wave bolus (whereby the insulin dose for the is delivered in 2 parts over 2 hours) via was found to achieve a greater reduction in postprandial glucose over a standard bolus12.

GI in pre-diabetes Lifestyle interventions that bring about weight loss will improve insulin resistance in and obese people with pre-diabetes. Comparison of a 3-month low- and high-GI diet and exercise intervention in obese a low GI diet the risk of a large-for- years, Hodge et. al 21 found that higher- adults with pre-diabetes found gestational-age infant was signifi cantly carbohydrate diets were associated that both induced weight loss and lower15 and the need for insulin to with a lower risk of development of improved hepatic and peripheral control much lower16 type 2 diabetes. However, the type of insulin sensitivity13. However, only compared to a high GI diet. A recent carbohydrate was extremely important: the low GI diet reduced postprandial RCT found similar foetal and maternal low-GI carbohydrates reduced the risk, insulin secretion whereas the high outcomes, however, with a low GI diet while high-GI carbohydrates increased GI diet maintained hyperinsulinemia compared with a conventional high the risk. exacerbating ß-cell dysfunction. fi bre diet17. Another study found an association between a high GI diet and 18 Observational studies suggest that risk of developing GDM . Summary following a low GI diet could delay or prevent the progression from pre- Protection against type 2 diabetes Benefi ts of a low GI * 14 diabetes to diabetes . Epidemiological studies19 and clinical include: trials20 have shown that low GI and • improved glycemic control GI in (GDM) low GL diets protect against type 2 • improved insulin sensitivity To-date, few studies have looked at the diabetes. Of note however, is that while • reduction in insulin resistance effect of GI and the risk of developing low GI and low GL are associated with • reduced risk of vascular disease GDM. However, of those that have, prevention, a low carbohydrate intake • assistance with weight loss most support the benefi t of a low GI is not. In their prospective analysis of a diet in the treatment of GDM. On cohort of ~36,000 adults followed for 4

*For references cited go to www.gisymbol.com/resources. Glycemic Index Foundation For more information on low GI diets and diabetes visit Phone: +61 (0)2 9020 6112 www.gisymbol.com Fax: +61 (0)2 9966 0172 email: [email protected] © 2012 Glycemic Index Foundation, All Rights Reserved. www. gisymbol.com ® The GI Symbol is a registered trademark of Glycemic Index Ltd.