Table 1 Clinical and biochemical characteristics of the enrolled patients before surgery

Sex, n (%)

0.32

 Female

320 (79.4%)

143 (81.7%)

177 (77.6%)

 Male

83 (20.6%)

32 (18.3%)

51 (22.4%)

Age (years), mean (SD)

47.0 (10.1)

47.6 (10.0)

46.5 (10.2)

0.28

Type of surgery, n (%)

0.48

 Roux-en-Y gastric bypass

277 (68.7%)

117 (66.9%)

160 (70.2%)

 Sleeve gastrectomy

126 (31.3%)

58 (33.1%)

68 (29.8%)

Body mass index (kg/m2), mean (SD)

45.0 (6.7)

45.2 (6.6)

44.9 (6.8)

0.71

Serum Mg (mEq/L), mean (SD)

1.53 (0.17)

1.39 (0.12)

1.64 (0.1)

 < 0.001

 < 0.001

Serum Mg < 1.52 mEq/L, n (%)

175 (43.4%)

Vitamin D (ng/mL), mean (SD)

15.6 (8.5)

17.7 (9.4)

14.2 (8.0)

0.03

0.77

HbA1c (%), mean (SD)

6.8 (1.4)

7.2 (1.6)

6.4 (1.0)

 < 0.001

 < 0.001

Fasting plasma glucose (mg/dL), mean (SD)

130.1 (49.6)

146.2 (58.8)

117.5 (36.3)

 < 0.001

 < 0.001

Fasting plasma insulin (mU/L), mean (SD)

25.2 (20.1)

24.8 (21.4)

25.5 (19.3)

0.81

0.47

Fasting plasma C-Peptide (ng/mL), mean (SD)

4.4 (1.7)

4.4 (1.9)

4.5 (1.5)

0.85

0.90

HOMA-IR, mean (SD)

8.2 (7.6)

9.0 (9.2)

7.6 (6.3)

0.25

0.92

No. of anti-diabetics, median (IQR)

1.0 (0–1.0)

1.0 (0–2.0)

1.0 (0–1.0)

0.003

0.002

Oral magnesium supplementation, n (%)

0.003

0.001

 Yes

15 (3.8%)

12 (7.1%)

3 (1.3%)

 No

388 (96.2%)

163 (92.9%)

225 (98.7%)

Total cholesterol (mg/dL), mean (SD)

201.2 (43.3)

194.5 (42.3)

206.5 (43.5)

0.006

0.003

LDL-cholesterol (mg/dL), mean (SD)

124 (37.6)

116.5 (36.5)

129.9 (37.5)

 < 0.001

 < 0.001

HDL-cholesterol (mg/dL), mean (SD)

48.1 (10.8)

48.0 (11.6)

48.1 (10.1)

0.96

0.75

Triglycerides (mg/dL), mean (SD)

166.6 (99.9)

179.9 (117.5)

156.3 (82.5)

0.019

0.011