Alterations in serum levels of 1 α,25(OH) 2 D 3 and osteocalcin in patients with early diabetic nephropathy

Abstract

Serum levels of markers for bone remodeling and diabetic metabolic markers were measured in subjects with non-insulin-dependent diabetes mellitus (NIDDM) to investigate the relationship between early diabetic nephropathy and calcium/bone metabolism. 1 α,25(OH) 2 D 3 (Vit D), osteocalcin (OC), intact parathyroid hormone (PTH) and urine albumin excretion (UAE) were measured in all subjects. Serum levels of Vit D and OC were significantly decreased in diabetic subjects compared to age-matched, non-diabetic controls. In diabetic patients, a significant positive correlation was observed between intact PTH and OC. No significant correlation was found between levels of Vit D and OC. In early diabetic nephropathy without increased serum creatinine, Vit D decreased and OC increased with increasing UAE. Levels of hemoglobin A 1c (HbA 1c) and fructosamine (FRA) were not correlated with levels of Vit D or OC. Levels of Vit D were decreased and levels of OC were increased in diabetic subjects with proliferative retinopathy or with micro- or macro-albuminuria. Conclusions: Results of the present study indicate that changes in bone remodeling markers such as Vit D and OC levels are present in the early stages of diabetic nephropathy, and that circulating intact PTH is important in restoring the reduced OC levels in diabetic patients, probably as a reflection of bone remodeling.