Association between body mass index and lumbar spine volumetric bone mineral density in diabetic and non-diabetic patients

Table 1 Demographic and clinical characteristics of study population

Variable	Total	Obesity		Overweight		Normal weight
	n = 1967	Diabetes, n = 162	Non-diabetes, n = 370	Diabetes, n = 184	Non-diabetes, n = 683	Diabetes, n = 81	Non-diabetes, n = 487
Age (years)	59.4 ± 6.7	59.5 ± 6.1	58.8 ± 6.2	59.8 ± 6.9	59.2 ± 6.8	61.1 ± 6.8	59.8 ± 7.20
Men (%)	49.1	35.8	37.3	53.8	50.7	54.3	57.7
Annual household income (%)
< ¥50000	60.3	53.7	57.0	48.9	60.8	65.4	67.8
¥50000-99000	30.1	32.1	33.6	36.9	30.0	22.2	25.9
≥ ¥100000	9.5	14.2	9.5	14.2	9.2	12.4	6.4
Education (%)
Elementary school or lower	33.6	39.5	33.2	29.3	29.9	45.7	36.8
Middle school	60.0	51.9	60.9	59.7	62.4	54.3	59.8
College or higher	6.4	8.7	5.7	10.8	7.7	0	3.5
BMI (kg/m2)	26.09 ± 3.47	30.53 ± 2.25	30.40 ± 2.22	25.97 ± 1.15	26.01 ± 1.14	22.35 ± 1.21	22.12 ± 1.34
WC (cm)	88.0 ± 9.6	99.0 ± 6.9	97.6 ± 6.9a	89.8 ± 6.1	87.5 ± 5.9b	80.5 ± 5.5	80.0 ± 5.7
HC (cm)	98.4 ± 6.9	104.9 ± 5.9	105.2 ± 6.2	97.3 ± 4.7	98.3 ± 4.7b	92.3 ± 5.04	92.7 ± 4.7
WHR	0.89 ± 0.07	0.94 ± 0.06	0.93 ± 0.06a	0.92 ± 0.06	0.89 ± 0.06b	0.87 ± 0.06	0.84 ± 0.06b
ALT (U/L)	22.5 ± 12.2	28.8 ± 20.6	23.9 ± 10.8b	24.1 ± 16.7	22.2 ± 11.0a	19.3 ± 8.9	19.6 ± 7.8
AST (U/L)	23.3 ± 8.9	28.5 ± 14.4	23.5 ± 8.7	23.2 ± 13.8	23.0 ± 7.2a	21.1 ± 8.0	23.2 ± 6.0b
Cr (μmol/L)	63.4 ± 33.6	61.6 ± 17.3	62.0 ± 14.2	68.4 ± 56.9	62.1 ± 14.5	76.6 ± 103.7	62.8 ± 31.5
FPG (mmol/L)	6.38 ± 1.81	8.59 ± 2.28	5.80 ± 0.54b	8.44 ± 2.23	5.76 ± 0.58b	9.54 ± 3.81	5.64 ± 0.55b
FINS (uIU/mL)	9.25 ± 6.88	15.55 ± 10.09	12.02 ± 6.19b	11.19 ± 10.16	8.57 ± 4.11b	7.42 ± 11.53	5.60 ± 3.00
HbA1c (%)	6.03 ± 1.04	7.31 ± 1.36	5.80 ± 0.47	7.12 ± 1.34	5.69 ± 0.40b	7.30 ± 1.80	5.62 ± 0.70b
HOMA-IR	2.74 ± 2.69	6.07 ± 4.63	3.14 ± 1.82b	4.22 ± 4.10	2.22 ± 1.16b	3.04 ± 4.94	1.42 ± 1.84b
SBP (mmHg)	133 ± 18	137 ± 17	136 ± 18	137 ± 19	132 ± 16	136 ± 21	130 ± 18
DBP (mmHg)	79 ± 11	81 ± 11	82 ± 12	79 ± 10	79 ± 10	75 ± 11	76 ± 11a
Cholesterol (mmol/L)	5.09 ± 1.41	5.27 ± 1.31	5.15 ± 1.09	5.15 ± 1.12	5.03 ± 0.94	5.14 ± 1.21	5.04 ± 0.92
Triglyceride (mmol/L)	1.59 ± 1.41	2.26 ± 1.49	1.87 ± 1.51b	2.00 ± 2.01	1.51 ± 1.13b	1.41 ± 1.24	1.13 ± 1.21a
LDL-C (mmol/L)	2.98 ± 0.84	3.06 ± 0.91	3.07 ± 0.91	2.97 ± 0.93	2.99 ± 0.78	2.89 ± 0.93	2.91 ± 0.77
HDL-C (mmol/L)	1.18 ± 0.31	1.06 ± 0.18	1.09 ± 0.24	1.11 ± 0.29	1.17 ± 0.27b	1.30 ± 0.44	1.33 ± 0.36
vBMD	103.0 ± 30.8	105.9 ± 33.2	102.1 ± 29.4	104.0 ± 32.9	103.9 ± 30.6	101.6 ± 30.4	100.8 ± 30.9

^aP < 0.05.

^bP < 0.01.

BMI: Body mass index; WC: Waist circumference; HC: Hip circumference; WHR: Waist hip rate; ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; Cr: Creatinine; FPG: Fasting plasma glucose; FINS: Fasting insulin; HbA1c: Hemoglobin A1c; HOMA-IR: Homeostasis model assessment of insulin resistance; SBP: Systolic blood pressure; DBP: Diastolic blood pressure; LDL-C: Low-density lipoprotein cholesterol; HDL-C: High-density lipoprotein cholesterol; vBMD: Volumetric bone mineral density.

Table 2 Saturation effect analysis of body mass index and volumetric bone mineral density

	Diabetes		Non-diabetes		Total
	β (95%CI)	P value	β (95%CI)	P value	β (95%CI)	P value
vBMD
Model 1
One line effect	0.54 (-0.20, 1.29)	0.155	0.40 (0.01, 0.78)	0.043	0.43 (0.09, 0.77)	0.014
Model 2
BMI turning point (K), kg/m2	29.24		21.48		21.42
< K, effect 1	0.28 (-0.81, 1.38)	0.612	3.84 (0.41, 7.26)	0.028	3.70 (0.33, 7.08)	0.032
> K, effect 2	1.12 (-0.83, 3.06)	0.261	0.21 (-0.22, 0.64)	0.339	0.28 (-0.09, 0.66)	0.139
Effect 2 - 1	0.83 (-1.77, 3.43)	0.532	-3.63 (-7.22, -0.04)	0.048	-3.42 (-6.93, 0.09)	0.056
LRT test		0.529		0.047		0.056
Men
Model 1
One line effect	0.33 (-0.86, 1.52)	0.589	0.53 (-0.08, 1.15)	0.043	0.49 (-0.06, 1.04)	0.080
Model 2
BMI turning point (K), kg/m2	26.45		22.33		21.65
< K, effect 1	1.07 (-1.26, 3.39)	0.370	3.51 (0.56, 6.46)	0.020	3.93 (0.14, 7.72)	0.042
> K, effect 2	-0.33 (-2.48, 1.82)	0.763	0.05 (-0.73, 0.82)	0.907	0.19 (-0.45, 0.83)	0.567
Effect 2 - 1	-1.40 (-5.18, 2.38)	0.470	-3.46 (-6.82, -0.11)	0.043	-3.74 (-7.82, 0.34)	0.072
LRT test		0.465		0.043		0.072
Women
Model 1
One line effect	0.7 (-0.2, 1.7)	0.133	0.4 (-0.1, 0.8)	0.143	0.49 (-0.06, 1.04)	0.080
Model 2
BMI turning point (K), kg/m2	27.3		28.7		29
< K, effect 1	-0.2 (-2.4, 2.0)	0.844	-0.1 (-0.8, 0.6)	0.760	-0.1 (-0.7, 0.6)	0.879
> K, effect 2	1.4 (-0.3, 3.1)	0.108	1.3 (0.1, 2.5)	0.035	1.4 (0.4, 2.5)	0.009
Effect 2 - 1	1.6 (-1.8, 5.0)	0.347	1.4 (-0.2, 3.0)	0.096	1.5 (0, 3.0)	0.049
LRT test		0.342		0.095		0.049

BMI: Body mass index; vBMD: Volumetric bone mineral density; LRT: Likelihood ratio test.