The in vivo glycaemic response of different rice varieties in Sri Lanka

Introduction: Diabetes poses a heavy economic burden in Sri Lanka. High glycaemic index (GI) diets are known to promote a higher risk of diabetes. This study was aimed to determine the GI values of nine improved and three traditional rice varieties of Sri Lanka including Bg406, H.H.Z.36, Ld368, Bw367, Bg94-1, At405, At362, Bg300, Bg352, Sudu heenati, Madathawalu, and Pachchaperumal. Furthermore, comparisons of GI values between improved and traditional varieties, as well as the effect of subject gender and colour of pericarp on GI were described. Methods: Fourteen healthy subjects consisting of seven males and seven females were fed with a reference food and cooked rice varieties containing 50 g available carbohydrate; GI were calculated. Results: The GI of 12 rice varieties varied from 40-69. All traditional varieties including Sudu heenati, Madathawalu and Pachchaperumal were in the low GI category presenting GI values of 51, 54, and 41, respectively. Rice with red pericarp obtained significantly lower GI compared to those with white pericarp. Yet, GI values obtained in males were significantly higher than females. Conclusion: The result of this study suggested that all traditional varieties and improved rice H.H.Z 36, Ld368, and Bg406 could have beneficial effects on lowering the glycaemic response in healthy subjects. Glycaemic index can be predicted from the colour of the rice grain. Gender should be considered in the determination of GI.

Estimating heritability of glycaemic response to metformin using nationwide electronic health records and population-sized pedigree

Background Variability of response to medication is a well-known phenomenon, determined by both environmental and genetic factors. Understanding the heritable component of the response to medication is of great interest but challenging due to several reasons, including small study cohorts and computational limitations. Methods Here, we study the heritability of variation in the glycaemic response to metformin, first-line therapeutic agent for type 2 diabetes (T2D), by leveraging 18 years of electronic health records (EHR) data from Israel’s largest healthcare service provider, consisting of over five million patients of diverse ethnicities and socio-economic background. Our cohort consists of 80,788 T2D patients treated with metformin, with an accumulated number of 1,611,591 HbA1C measurements and 4,581,097 metformin prescriptions. We estimate the explained variance of glycated hemoglobin (HbA1c%) reduction due to inheritance by constructing a six-generation population-size pedigree from national registries and linking it to medical health records. Results Using Linear Mixed Model-based framework, a common-practice method for heritability estimation, we calculate a heritability measure of $${h}^{2}=12.6 \%$$ h 2 = 12.6 % (95% CI, $$6.1 \%\! -\!19.1 \%$$ 6.1 % − 19.1 % ) for absolute reduction of HbA1c% after metformin treatment in the entire cohort, $${h}^{2}=21.0 \%$$ h 2 = 21.0 % (95% CI, $$7.8 \%\! -\!34.4 \%$$ 7.8 % − 34.4 % ) for males and $${h}^{2}=22.9 \%$$ h 2 = 22.9 % (95% CI, $$10.0 \%\! -\!35.7 \%$$ 10.0 % − 35.7 % ) in females. Results remain unchanged after adjusting for pre-treatment HbA1c%, and in proportional reduction of HbA1c%. Conclusions To the best of our knowledge, our work is the first to estimate heritability of drug response using solely EHR data combining a pedigree-based kinship matrix. We demonstrate that while response to metformin treatment has a heritable component, most of the variation is likely due to other factors, further motivating non-genetic analyses aimed at unraveling metformin’s action mechanism.

Glycaemic potency reduction by coarse grain structure in breads is largely eliminated during normal ingestion

The hypothesis that coarse grain particles in breads reduce glycaemic response only if the particles remain intact during ingestion was tested. Three breads were formulated: (1) White bread (WB - reference), (2) 75% of kibbled purple wheat in 25% white bread matrix (PB), (3) a 1:1 mixture of 37.5% kibbled soy beans and 37.5% of kibble purple wheat in 25% white bread matrix (SPB). Each bread was ingested in three forms: unchewed (U), as customarily consumed (C), and homogenized (H). Twelve participants ingested 40 g available carbohydrate portions of each bread in each form, with post prandial blood glucose measured over 120 min. Glycaemic responses to WB were the same regardless of its form when ingested. Unchewed PB had significantly less glycaemic effect than WB, whereas the C and H forms were similar to WB. Based on a glycaemic index (GI) of 70 for WB the GI values for the C, U and H breads respectively were WB: 70.0, 70, 70, PB: 75, 42, 61, SPB: 57, 48, 55 (%) (Least significant difference = 17.43, p <0.05, bold numbers significantly different from WB). The similar glycaemic response to the H and C forms of the breads, and their difference from the U form, showed that the glycaemia-moderating effect of grain structure on starch digestion was lost during customary ingestion of bread. We conclude that kibbled grain structure may not effectively retard starch digestion in breads as normally consumed because it is largely eliminated by ingestive processes including chewing.

The effect of a breakfast’s glycaemic index and type of hydration on metabolism and cycling performance: a crossover, randomized, controlled clinical trial. [El efecto del índice glucémico del desayuno y el tipo de hidratación en el metabolismo y el rendimiento del ciclismo: un ensayo clínico cruzado, aleatorizado y controlado].

The purpose of this study was to compare the effect of the glycaemic index of breakfast on metabolic parameters and performance of cyclists with different types of hydration (water or isotonic beverage). Twelve male recreational cyclists participated in four experimental trials where they consumed either a high glycaemic index (HGI) or low glycaemic index (LGI) meal, 30 min before exercise on a cycle ergometer. Exercise was performed at 70% maximal oxygen uptake for 90 min followed by a 6 km performance. During each trial, 3 mL.kg-1 body mass of either water or isotonic beverage was provided. The postprandial glycaemic response and areas under the blood glucose curve 30 min after ingestion were higher after the consumption of the HGI meals than that after the consumption of the LGI meals. The glycaemic response and carbohydrate oxidation during the trials with isotonic beverage consumption were higher than that in trials with water consumption during exercise (p<0.05). There was no significant difference on exercise performance among all trials (p=0.409). This study demonstrated that, despite significant metabolic changes, neither LGI nor HGI meals consumed for breakfast, 30 min before exercise on a cycle ergometer, affect subsequent cycling performance.