Glucose-loading reduces bone remodeling in women and osteoblast function in vitro

Area of Science:

• Endocrinology
• Bone Biology
• Metabolic Health

Background:

• Aging diminishes osteoblast lifespan and bone formation, leading to microstructural deterioration.
• Aging is linked to insulin resistance and hyperglycemia, potentially decreasing undercarboxylated osteocalcin (ucOC), which enhances insulin sensitivity.

Purpose of the Study:

• To investigate if glucose loading impacts bone remodeling and ucOC in vivo.
• To determine if glucose affects osteoblast function in vitro, compromising bone formation.

Main Methods:

• Oral glucose tolerance tests (OGTT) were performed on 18 women (pre/postmenopausal, non-diabetic) at rest and post-exercise.
• Serum bone remodeling markers (BRMs) and ucOC levels were measured.
• Human osteoblasts were cultured to assess the effects of varying glucose and insulin concentrations on cell survival and activity.

Main Results:

• Glucose loading reduced BRMs in all women and ucOC in postmenopausal women.
• Elevated glucose levels negatively correlated with BRMs and ucOC, while insulin showed a positive correlation.
• High glucose concentrations (>10 mmol/L) in vitro increased osteoblast apoptosis and reduced cell activity and osteocalcin expression, an effect mitigated by insulin.

Conclusions:

• Glucose exposure suppresses bone remodeling markers in women, an effect not attenuated by exercise.
• Impaired osteoblast function and longevity likely mediate glucose's suppressive effect on bone remodeling.
• Further research is needed to ascertain glucose's impact on bone material composition and microstructure.