Effect of lifestyle interventions with or without metformin therapy on serum levels of osteoprotegerin and receptor activator of nuclear factor kappa B ligand in patients with prediabetes

Osteoprotegerin has been shown to be increased in cardiovascular disorders and type 2 diabetes mellitus. Prediabetes represents a high risk condition for diabetes and diabetic complications. Therefore, we aimed to find the relationship between prediabetes and osteoprotegerin with nuclear factor-B ligand, carotid intima media thickness, and metabolic markers. A total of 54 participants with prediabetes including impaired fasting glucose (n = 21), impaired glucose tolerance (n = 8), impaired fasting glucose and impaired glucose tolerance (n = 25), and 60 healthy individuals as a control were admitted to the study. Metabolic and anthropometric parameters, insulin resistance variables, osteoprotegerin, and nuclear factor-B ligand markers, carotid intima media thickness were examined at baseline for all participants. To evaluate the effect of therapy we determined the same parameters after the end of the study. Measurements of waist circumference, body mass index, body fat percentage and levels of fasting blood glucose, fasting insulin, homeostatic model assessment of insulin resistance, triglyceride levels and hsCRP and carotid intima media thickness were significantly higher in patients with prediabetes (p < 0.05). We also found higher osteoprotegerin and lower nuclear factor-B ligand levels in patients than in controls however, the value was non-significant (p > 0.05). Patients with prediabetes were under lifestyle interventions with (group 1, n = 33) or without metformin (group 2, n = 21) therapy. Baseline anthropometric and metabolic characteristics were not found statistically different in group 1 and group 2. Mean follow up period of the patients were 7.9 +/- 2.2 month (min-max: 6-12 months). After the follow up period we evaluated the same parameters and found significant differences between waist circumference, body mass index, body fat percentage, fasting insulin, homeostatic model assessment of insulin resistance, and osteoprotegerin levels (p < 0.05). However, carotid intima media thickness, and nuclear factor-B ligand levels significantly different only in the group treated with metformin (p < 0.05). We also compared the variables after the treatment period with the control group and found significantly lower levels in terms of fasting insulin, homeostatic model assessment of insulin resistance, waist circumference, body mass index, body fat percentage, carotid intima media thickness, osteoprotegerin, and nuclear factor-B ligand values (p < 0.05). Correlation analysis revealed a negative relationship between nuclear factor-B ligand and body mass index, and body fat percentage in group 1 (p = 0.05, r = -0.646, p = 0.01, r = -0.585). Therapy of prediabetes was associated with a significant decrease in osteoprotegerin and certain metabolic variables together with an increase in nuclear factor-B ligand levels particularly in patients with under metformin therapy.