Glycaemic index: challenges in translating concept to practice

Abstract

Dietary prescribing in diabetes mellitus based on glycaemic index (GI) of foods has always been an attractive concept. Food choices with lower GI are associated with lower glucose responses after consumption and hence would be the preferred choices in patients with diabetes. While this idea has been very promising, the real challenge over the years has been its implementation in day to day practice. Several issues like validity and reproducibility of GI measurements, factors affecting glycaemic responses, differences when consumed as single foods or in mixed meals and amount of absorbable/ digestable carbohydrate need consideration besides other methodological concerns.The concept of GI has evolved over time. When it was first proposed [1], it measured the glycaemic response of a test food as a percentage of the glycaemic response of a reference food containing a similar amount of carbohydrate. The reference food has traditionally been glucose or white bread. Even this lead to variability of GI values depending on whether it was glucose or white bread that was the reference. Individual foods have been tested and categorized as low, medium or high GI foods based on their glycaemic responses [2] when consumed alone. However, these values lose significance when the foods are consumed as part of a mixed meal [3].The concept of GI does not take into account the amount of carbohydrate consumed even though this is a major determinant of the glycaemic response. This lead to the extension of the concept of GI to glycaemic load (GL) which is the product of GI and the total amount of carbohydrate consumed [4]. GL gives a fair idea of the glucose load or burden that results from the ingestion of a carbohydrate containing meal. A high GI food can have a low GL if the portion size consumed is small and a low GI food can have a high GL if the serving size is big.It has also been realized that all carbohydrate in food is not available for conversion to glucose and hence only the amount of "available" carbohydrate also called glycaemic carbohydrate and not total carbohydrate should be used for calculation of GI. What constitutes available carbohydrate has also been a subject of debate and the consensus view is that the undigestable carbohydrate which includes the fibre and all resistant starch is taken as unavailable [5].There are several limitations to the usefulness of GI and GL. Studies suggest that GI could be affected by many factors including the amounts of other nutrients such as fat, protein and fibre, structure of the carbohydrate, particle size, food form, food processing and cooking method [5]. These factors lead to a lot of intra and inter individual variability of GI values and GL making these estimates less reliable and raise questions about their validity [6]. The rates of digestion of carbohydrates also vary with health status, race, gender and underlying insulin resistance all of which can affect GI [5]. Similarly, methodological differences such as the amount of tested food which contains 50 g of carbohydrate (...

Nutrition Education Regarding the Glycemic Index on the Knowledge of Patients with Diabetes Mellitus

“…Education about the glycemic index of food to diabetic patients is needed as a diabetes prevention and control measure. Good knowledge of the glycemic index needs to be possessed by diabetic patients as a basis for good practice in controlling dietary patterns [20]. The previous studies have shown that most diabetic patients have insufficient knowledge, so education in diabetes management is needed [21].…”

A Comparative Study on the Carbohydrate proৎile and In-vitro Glycaemic Index of Processed Basil (Ocimum basilicum) Seeds Incorporated Idlis

“…The study result of (Zafar et al, 2019) has proved that the low-GI diets reduce glycated hemoglobin (HbA1c) levels, fasting blood glucose levels, BMI, total cholesterol, and LDL, but had no effect on fasting insulin, HOMA-IR, HDL, triglycerides, or insulin requirements. Even with these limitations, GI continues to capture the attention of physicians and nutritionists alike as it does offer a rational way of ranking carbohydrate-containing foods that has the potential to favorably affect the prevention and management of diabetes (Madhu, 2017). Idli, a South Indian staple diet which had been into controversies in recent times, has been acknowledged as a wholesome, nutritious food by many health professionals.…”