Effect of inulin from dahlia tubers (Dahlia variabilis) extract on insulitis severity and insulin expression in diabetic rats.

Background: Dahlia (Dahlia variabilis), a widely cultivated ornamental plant in Indonesia, is known to contain 84.08% inulin in its tubers. Numerous studies have demonstrated the antidiabetic potential of inulin from various plant sources. However, most of the research is in the form of a mixture of inulin with other active substances, and no one has analyzed the effects of inulin derived from dahlia tubers. This study examines the effect of inulin from dahlia tuber extract on blood glucose levels, serum insulin expression, pancreatic tissue insulin expression, homeostatic model assessment of insulin resistance (HOMA-IR), and the extent of insulitis in diabetic rats.

Methods: In this experimental study, 20 male Wistar rats were randomly allocated to five groups. Group I served as the control, Group II as the STZ-induced diabetic group, Group III as the STZ-induced diabetic group treated with inulin (0.5 g/kgBW), Group IV as the STZ induced diabetic group treated with inulin (1.0 g/kgBW), and Group V as the STZ-induced diabetic group treated with inulin (1.5 g/kgBW). The inulin was administered for 21 days. The degree of insulitis was evaluated using a scoring system, serum insulin concentration via ELISA, and insulin expression in the pancreas through immunohistochemistry.

Results: Administration of inulin from dahlia tubers significantly reduced serum glucose concentrations in diabetic rats. Notably, only inulin extracts at doses of 1 g/kgBW and 1.5 g/kgBW showed a significant reduction in insulitis and HOMA-IR index in diabetic rats, while the 0.5 g/kgBW inulin extract reduced insulitis without affecting HOMA-IR. Inulin extract administration did not affect insulin expression in serum or pancreatic tissue.

Conclusions: Inulin from dahlia tuber can exert antidiabetic properties by improving insulin resistance and insulitis. These studies suggest the great potential of dahlia tubers as the source of inulin for prebiotic functional foods.