Are excess carbohydrates the main link to diabetes & its complications in Asians?

Abstract

Dietary carbohydrates form the major source of energy in Asian diets. The carbohydrate quantity and quality play a vital function in the prevention and management of diabetes. High glycaemic index foods elicit higher glycaemic and insulinaemic responses and promote insulin resistance and type 2 diabetes (T2D) through beta-cell exhaustion. This article reviews the evidence associating dietary carbohydrates to the prevalence and incidence of T2D and metabolic syndrome (MS) in control of diabetes and their role in the complications of diabetes. Cross-sectional and longitudinal studies show that higher carbohydrate diets are linked to higher prevalence and incidence of T2D. However, the association seems to be stronger in Asian-Indians consuming diets high in carbohydrates and more marked on a background of obesity. There is also evidence for high carbohydrate diets and risk for MS and cardiovascular disease (CVD). However, the quality of carbohydrates is also equally important. Complex carbohydrates such as brown rice, whole wheat bread, legumes, pulses and green leafy vegetables are good carbs. Conversely, highly polished rice or refined wheat, sugar, glucose, highly processed foods such as cookies and pastries, fruit juice and sweetened beverages and fried potatoes or French fries are obviously ‘bad’ carbs. Ultimately, it is all a matter of balance and moderation in diet. For Indians who currently consume about 65-75 per cent of calories from carbohydrates, reducing this to 50-55 per cent and adding enough protein (20-25%) especially from vegetable sources and the rest from fat (20-30%) by including monounsaturated fats (e.g. groundnut or mustard oil, nuts and seeds) along with a plenty of green leafy vegetables, would be the best diet prescription for the prevention and management of non-communicable diseases such as T2D and CVD.