Bone turnover markers (BTMs) are reduced in diabetes, but whether BTM changes occur in impaired fasting glucose (IFG) is unknown. The aim of this study was to investigate whether BTMs are altered in IFG and diabetes compared to normoglycaemia. For men and women (n = 2222) in the Geelong Osteoporosis Study, IFG was defined as fasting plasma glucose (FPG) 5.5-6.9 mmol/L and diabetes as FPG ≥ 7.0 mmol/L, use of antihyperglycemic medication and/or self-report. Serum C-terminal telopeptide (CTx) and procollagen type 1 N-terminal propeptide (P1NP) were measured. After natural log transformation to normalise the data, multivariable regression was used to examine the relationship between glycaemia status and bone turnover markers (BTMs), before and after adjusting for other confounders. There were 643 men and 682 women with normoglycaemia, 355 men and 391 women with IFG and 97 men and 54 women with diabetes. Men with IFG or diabetes had lower adjusted ln(CTx) and ln(P1NP) compared to normoglycaemia (all p < 0.05). Women with IFG or diabetes had lower adjusted ln(CTx) and ln(P1NP) (all p < 0.05) except for ln(P1NP) when comparing diabetes with normoglycaemia, which showed a trend for lower ln(P1NP) (p = 0.053). In both sexes, an age * glycaemia interaction term indicated between-group differences in BTMs diminished with increasing age. No other confounders were identified. Bone turnover was lower in those with either IFG or diabetes compared to normoglycaemia.
Keywords: Bone turnover markers; Diabetes mellitus; Impaired fasting glucose.