Glycemic Index of Products Derived from Sweetpotato When Compared to Their Analog White Potato Product

Glycemic index (GI) ranks carbohydrate-containing foods according to their effect on blood sugar as low (55 or less), moderate (56-69) and high (70 or above) categories. Our objective was to study the GI for processed sweetpotato (SP) (chips, fries, dehydrated granules and juice) compared to a similar white potato (WP) food. Continuous glucose monitoring (CGM) was compared to glycemic index using capillary blood from finger-pricks.Ten subjects consumed each food on three separate occasions. From glucose responses for each product and method of collection (capillary and CGM), incremental AUC and net AUC were calculated from trapezoidal areas in graphs.GI (mean ±SEM) for SP chips were significantly lower than WP chips, with capillary blood iAUC values of 32.7±1.96 and 53.1±3.21 mg*min respectively. Sweetpotato fries and WP fries were 48.7±2.85 and 57.9±3.76 (p>0.05). Sweetpotato and WP granules had GI means of 39.6 ±3.24 and 69.8±4.15 respectively, and SP juice GI was 79.1±4.82 mg*min. For all products, data collected from CGM or from capillary blood were not different.Conclusion: GI of SP chips and powders were lower than WP analogs and lower than previous reports for fresh SP, possibly due to factors like fat content, creation of poorly-digestible resistant starches during processing, insoluble fiber, and other non-digestible carbohydrates in powders and juice. GI values for WP fries were consistent with previous GI values. The iAUC and net AUC calculation were similar. CGM may be a simpler method for future glycemic index studies.