Glycemic control and anti-osteopathic effect of propolis in diabetic rats

The aim of the study was to explore the possibility that propolis can control diabetes mellitus and prevent diabetic osteopathy in rats. The study compared 60 streptozotocin (STZ)-induced diabetic rats, with ten nondiabetic rats used as a negative control. The experimental design comprised seven groups (n = 10 rats per group): (1) nondiabetic, used as a negative control; (2) nontreated, used as a positive control; (3) treated with insulin alone; (4) treated with a single dose of propolis alone; (5) treated with a double dose of propolis; (6) treated with insulin and a single dose of propolis; and (7) treated with insulin and a double dose of propolis. After 6 weeks of treatment, the rats were sacrificed. Ratios of femur ash to femur weight and of femur weight to body weight (FW/BW) were calculated and calcium (Ca), phosphorus (P), and magnesium (Mg) concentrations in femur ash were estimated and analyzed. Fasting blood glucose (FBG), plasma insulin and glucagon, serum thiobarbituric acid reactive substances (TBARS), plasma parathyroid hormone (PTH), and calcitonin levels were also estimated and analyzed. There was significant reduction in FBG in all diabetic treated rats. Similarly, higher plasma insulin levels were observed in diabetic rats treated with propolis and insulin than in nontreated diabetic rats, although plasma insulin was not comparatively higher in diabetic rats treated with insulin alone. Serum TBARS was significantly lower in the propolis treated rats than the diabetic nontreated rats. No differences in PTH and calcitonin levels were observed among treatment groups. The FW/BW ratio was significantly higher in diabetic treated groups than in control groups. Furthermore, diabetic rats treated with propolis and insulin had significantly higher Ca, P, and Mg concentrations in femoral ash than nontreated diabetic rats and diabetic rats treated with insulin alone. In conclusion, propolis has a remarkable effect on glucose homeostasis and bone mineralization.