Combination of Obesity with Hyperglycemia is a Risk Factor for the Presence of Vertebral Fractures in Type 2 Diabetic Men

Although patients with type 2 diabetes show no bone mineral density (BMD) reduction, fracture risks are known to increase. It is unclear why the patients have an increased risk of fracture despite sufficient BMD. We investigated the relationships of body mass index (BMI), HbA_1c, and urinary C-peptide (uC-peptide) versus BMD, bone metabolic markers, serum adiponectin, and prevalent vertebral fracture (VF). A total of 163 Japanese type 2 diabetic men were consecutively recruited, and radiographic and biochemical data were collected. BMI was positively correlated with BMD at the whole body, lumbar spine, and femoral neck (P < 0.05) and negatively correlated with osteocalcin and urinary N-terminal cross-linked telopeptide of type-I collagen (uNTX) (P < 0.01). HbA_1c was negatively correlated with osteocalcin (P < 0.01) but not BMD at any site. Subjects were classified into four groups based on BMI and HbA_1c (group LL BMI < 24 and HbA_1c < 9, group LH BMI < 24 and HbA_1c ≧ 9, group HL BMI ≧ 24 and HbA_1c < 9, group HH BMI ≧ 24 and HbA_1c ≧ 9). Serum adiponectin, osteocalcin, and uNTX were lower and the incidence of VF was higher despite sufficient BMD in the HH group. Multivariate logistic regression analysis adjusted for age, duration of diabetes, uC-peptide, and estimated glomerular filtration rate showed that the HH group was associated with the presence of a VF and multiple VFs (odds ratio [OR] = 3.056, 95% confidence interval [CI] 1.031–9.056, P = 0.0439, and OR = 5.415, 95% CI 1.126–26.040, P = 0.0350, respectively). Combination of obesity with hyperglycemia was a risk factor for VF despite sufficient BMD in diabetic men.