The relation of low glycaemic index fruit consumption to glycaemic control and risk factors for coronary heart disease in type 2 diabetes

AIMS/HYPOTHESIS: Sugar has been suggested to promote obesity, diabetes and coronary heart disease (CHD), yet fruit, despite containing sugars, may also have a low glycaemic index (GI) and all fruits are generally recommended for good health. We therefore assessed the effect of fruit with special emphasis on low GI fruit intake in type 2 diabetes. METHODS: This secondary analysis involved 152 type 2 diabetic participants treated with glucose-lowering agents who completed either 6 months of high fibre or low GI dietary advice, including fruit advice, in a parallel design. RESULTS: Change in low GI fruit intake ranged from −3.1 to 2.7 servings/day. The increase in low GI fruit intake significantly predicted reductions in HbA(1c) (r = −0.206, p = 0.011), systolic blood pressure (r = −0.183, p = 0.024) and CHD risk (r = −0.213, p = 0.008). Change in total fruit intake ranged from −3.7 to 3.2 servings/day and was not related to study outcomes. In a regression analysis including the eight major carbohydrate foods or classes of foods emphasised in the low GI diet, only low GI fruit and bread contributed independently and significantly to predicting change in HbA(1c). Furthermore, comparing the highest with the lowest quartile of low GI fruit intake, the percentage change in HbA(1c) was reduced by −0.5% HbA(1c) units (95% CI 0.2–0.8 HbA(1c) units, p < 0.001). CONCLUSIONS/INTERPRETATION: Low GI fruit consumption as part of a low GI diet was associated with lower HbA(1c), blood pressure and CHD risk and supports a role for low GI fruit consumption in the management of type 2 diabetes. TRIAL REGISTRATION: ClinicalTrials.gov NCT00438698 FUNDING: The Canadian Institutes of Health Research; Canada Research Chair Endowment of the Federal Government of Canada, Loblaw Companies, and Barilla (Italy). ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00125-010-1927-1) contains supplementary material, which is available to authorised users.