glucose and increased serum insulin levels in aloe-treated rats compared to diabetic controls (Table 1). In agreement, previous authors claimed for such antidiabetic effect for aloe extract on experimental animals.18,19 Our in vitro results support this finding, where aloe was found to increase the rate of insulin secretion from pancreatic islets (Figs. 4 and 5). Many explanations were suggested for this antidiabetic effect
of aloe. The first explanation is the potent antioxidant effect of aloe extract. Aloe is long known to have antioxidant potential via suppression of free radical formation and
enhancement of cellular thiol status.20–22 It is also reported to stimulate glutathione-S-transferase enzyme activity.23 Our results strongly supported the antioxidant potential of aloe, where it was found to suppress elevated serum MDA levels and increase blood GSH and SOD levels. Recent approaches focus on the role of oxidative stress in pancreatic beta cell damage.8,24 That is, oxidative stress is involved as a causative
factor in the pathogenesis of diabetes, and hence antioxidants like aloe may have a true antidiabetic effect via antioxidant potential. The anti-inflammatory potential of aloe may be the second explanation for its antidiabetic effect. Diabetes may be considered
as an inflammatory disease where inflammation participates in the progression of diabetes, where tumor necrosis factor-a was found to decrease peripheral insulin sensitivity.25 Many authors claimed for the anti-inflammatory potential of aloe due to many of its components like emodin and mannose-6-phosphate.26,27 It was reported that the anti-inflammatory effect of aloe extract is comparable to that of hydrocortisone.28
Finally, aloe may act as a hypoglycemic agent through potent inhibition of pancreatic a-amylase activity.29 This action decreases starch breakdown and offers good postprandial glycemic control. These findings are promising for further clinical studies on
aloe extract or extract components in the management of diabetes mellitus.