Changes of serum osteocalcin, calcium, and potassium in a rat model of type 2 diabetes

Changes in serum levels of calcium (Ca), phosphorus (P), Ca phosphate, alkaline phosphatase (AKP), and osteocalcin (BGP) were assessed in a model of type 2 diabetes in 8-weeks-old Sprague-Dawley rats. Throughout the study, the animals in Group A consumed high-carbohydrate, high-fat diet and were administered two intraperitoneal injections of streptozocin (STZ) at 4 (25 mg/kg) and 8 (40 mg/kg) weeks after diet initiation. Animals in Group B received similar diet but intraperitoneal injections with citrate buffer. The control group rats (Group C) were fed normal diet and received citrate buffer injections. The Ca levels in Group A were significantly decreased at 12 and 16 weeks, while P levels were significantly lower at 8, 12, and 16 weeks after the first STZ injection (p < 0.05 vs. Groups B and C). The Ca phosphate levels in Group A were significantly lower at 16 weeks (p < 0.05 vs. Groups B and C). There was a discrepancy in kinetics of AKP and BGP levels in Group A, such that the former showed a significant surge at 8 weeks (p < 0.05 vs. Groups B and C) followed by a decline at 16 weeks (p < 0.05 vs. Groups B and C), while the levels of the latter consistently decreased and became significantly decreased at 12 and 16 weeks (p < 0.05 vs. Groups B and C). In conclusion, these findings may lead to better understanding of the pathogenesis of osteoporosis in diabetic rats.