This study examined the effects of a mixture of an aqueous extract of Salacia reticulata (Kotala himbutu) and cyclodextrin (SRCD) on various metabolic parameters and cecal fermentation in obese fa/fa male Wistar fatty rats, a model of type 2 diabetes mellitus. Wistar fatty rats were fed 0% (control group) or 0.2% SRCD-supplemented diets and weighed weekly. The plasma glucose, triacylglycerol, total cholesterol, insulin, and adiponectin concentrations were measured at weeks 0, 2, 4, and 5. SRCD supplementation suppressed the time-dependent increase in the plasma total cholesterol and insulin concentrations. After 6 weeks of a 0.2% SRCD-supplemented diet, the body weight gain, food intake, visceral fat mass, liver mass, and liver triacylglycerol content of the rats were significantly lower, whereas the plasma adiponectin concentrations were significantly higher than those of the control group. SRCD supplementation had no significant effect on plasma glucose and triacylglycerol concentrations. SRCD supplementation significantly increased cecum mass, whereas it significantly decreased the cecal butyrate and short-chain fatty acid (sum of the acetate, butyrate, and propionate) concentrations. All of the rats were subjected to an oral glucose tolerance test at the beginning of week 6. The area under the curve for insulin was significantly smaller with SRCD supplementation and showed no change in glucose tolerance compared to that of the control group. These results suggest that bioactive compounds in SRCD may suppress the development of type 2 diabetes mellitus by influencing glucose and lipid metabolism in male Wistar fatty rats and that SRCD may influence cecal fermentation.