Authors : Kaniz Fatema, Farzana Rahman, Nurunnahar Sumi, Khadizatul Kobura and Liaquat Ali
Abstract: Glycemic and Insulinemic responses to potato and sweet potato by estimating their Glycemic Index (GI) and insulinemic index (measured by c-peptide) from Bangladeshi origin were investigated in Type 2 Diabetic Mellitus (T2DM) patients. Based on serving size in the Bangladeshi society the GL of those two food items were also calculated. About 10 T2DM subjects (male 5, female 5, age 44±3.16 years, BMI 24±3.85, HbA1c 6.78±1.79%, M±SD) studied under a cross-over design, consumed equi-carbohydrate amount of the vegetables and white bread (WB, as reference food) with a run in period of 7 days between the consecutive items. The test meals (potato, sweet potato and WB) containing 50 g of total carbohydrate) were given to the participants for ingestion within 10 min with 200 mL water. Serum levels of glucose were estimated at 0, 15, 30, 45, 60, 90, 120, 150 and 180 min, respectively. GI and GL (serving size of the food 22 g for both potato and sweet potato, respectively in Bangladesh) were calculated by standard formulas. Serum glucose was measured by glucose-oxidase, c-peptide was used as the marker of insulin and was measured by chemiluminescent ELISA and HbA1c (glycosylated hemoglobin) by High-Performance Liquid Chromatography (HPLC) method. Classification of GI was taken from the international table (GI: high = 70, medium 56-69 and low = 55; GL: high = 20, medium 11-19 and low = 10). Both plain potato and sweet potato showed significantly higher serum glucose response compared to that of reference food (iAUC (M±SD): 234±65 in bread vs 361±81 in Potato and 416±47 in sweet potato; p<0.015 and 0.001, respectively). The similar glycemic response between plain potato and sweet potato was reflected in their GI values: 162±50 and 191±66, respectively. The basal values of serum insulin in all the 3 groups were matched. The substantially higher glycemic response and GI values in potato and sweet potato were not the consequence of a suppressed insulin response. The GL of potato and sweet potato were 8 and 11, respectively. Considering the economical aspect, crop production, high satiety, therapeutic advantage and for food diversity potato can be recommended for healthy as well as T2DM subjects especially for their low fat and high micronutrient content and beneficial effects in insulin response for some verities observed in this study. In spite of high GI, considering potential source of carbohydrate current consumption can possibly increased from a minor vegetable to the most important vegetable in the diet, as a mixed meal or and an occasional partial substitute for rice.
Kaniz Fatema, Farzana Rahman, Nurunnahar Sumi, Khadizatul Kobura and Liaquat Ali, 2010. Glycemic and Insulinemic Responses to Commonly Consumed Potatoes in Bangladeshi Type 2 Diabetic Subjects. Research Journal of Biological Sciences, 5: 345-349.