Comparative Effects of Low- and High-Glycemic Index Diets on Biochemical Variables and Organ Histology in Alloxanized Diabetic Rats

This experimentally-controlled designed study compared the effects of low- and high-glycemic index diets on biochemical variables and organ histology in alloxan-induced diabetic rats (DR).
Effects of low-GI (fried yam)and high-GI (roasted) diets on organ and body weights, pancreas histology, glycemic tolerance (GT) and lipid profile (LP) were determined and compared in the adult alloxan-induced (150mg/kg intraperitoneally) diabetic rats of 3 groups (8 rats each) fed with standard rat feed (control), fried and roasted yam diets respectively for six weeks. Lipid profile and glycemic tolerance were analysed and determined using a dry-chemical automatic analyzer and oral D"glucose load of 2gm kg"1 dissolved in distilled water respectively. Organs were extracted and weighed while pancreas histoarchitecture examined after 6 weeks of feeding. Data were analyzed using ANOVA and Student’s t test while values of P<0.05 were considered significant.
Postprandial glycemic response to low-GI (GI = 36%) diet showed improved GT (IAUC = 3082.5mg/dl.min) over that of high-GI (GI = 93%) diet (IAUC = 8332.0mg/dl.min). A significant increase (P<0.05) in mean body weight of rats was observed in all groups after six weeks of feeding with the highest increase (24.8%) observed in DR on high-GI diet (initial weight = 251.0±1.6g; final weight = 312.3±5.9g) and the lowest increase (9.2%) in DR on low-GI diet (initial weight = 250.7±1.1g; final weight = 273.2±1.7g). No significant change was observed in mean organ weights. Pancreas histology of DR on high-GI diet showed degeneration with degranulation and vacuolation of the islet β cells while regeneration of some β cells was observed in DR fed with low-GI diet. Triacylglycerides (52.2±1.0mg/dL) and cholesterol (60.5±1.5mg/dL) increased in DR fed with fried yam (low-GI) compared with those fed on roasted yam (high-GI).
The low-GI diet used in this study showed improved glycemic tolerance and histoarchitecture of pancreatic islets over that of high-GI diet. Although both diets are prepared from same source, difference in their processing methods reflects their observed impact on the biochemical variables. Fried yamas one of severally known low-GI diets may be incorporated in diabetic menu. However, long-term consumption of fatty foods should be avoided.