Table 1.
Patient demographics and baseline clinical characteristics n (%)
| Metformin group, n = 185 | Non-metformin group, n = 228 | P value | |
| Age at diagnosis in yr, mean ± SD | 63.5 ± 8.789 | 63.49 ± 10.218 | 0.991 |
| < 50 | 12 (6.5) | 27 (11.8) | 0.064 |
| ≥ 50 | 173 (93.5) | 201 (88.2) | |
| Sex | 0.921 | ||
| Male | 125 (67.6) | 153 (67.1) | |
| Female | 60 (32.4) | 75 (32.9) | |
| DM duration in yr, median (range) | 8 (1-120) | 6 (1-40) | 0.068 |
| Family history of CRC | 8 (4.3) | 13 (5.7) | 0.526 |
| BMI in kg/m2, mean ± SD | 23.6 ± 3.0 | 23.5 ± 3.0 | 0.596 |
| Normal < 25 | 148 (80.0) | 173 (76.5) | 0.300 |
| Overweight 25-30 | 33 (17.8) | 51 (22.6) | |
| Obese ≥ 30 | 4 (2.2) | 2 (0.9) | |
| Smoking | 0.371 | ||
| Never-smoker | 89 (48.1) | 123 (53.9) | |
| Ex-smoker | 42 (22.7) | 40 (17.5) | |
| Current smoker | 54 (29.2) | 65 (28.5) | |
| Alcohol | 0.556 | ||
| None | 82 (44.3) | 112 (49.1) | |
| < 1 drink/d | 42 (22.7) | 51 (22.4) | |
| ≥ 1 drink/d | 61 (33.0) | 65 (28.5) | |
| Aspirin use | 50 (27.0) | 39 (17.1) | 0.015 |
| Insulin use | 17 (9.2) | 27 (16.2) | 0.035 |
| Sulfonylurea use | 116 (62.7) | 153 (67.1) | 0.350 |
| Thiazolidinedione use | 18 (9.7) | 12 (5.3) | 0.082 |
| CEA in ng/mL, median (range) | 4.7 (0.2-9100.0) | 6.4 (0.1-5946.0) | 0.359 |
| HbA1c, mean ± SD | 8.7 ± 16.7 | 7.3 ± 1.4 | 0.349 |
| Glucose in mg/dL, AC ± SD | 143.8 ± 46.1 | 132.4 ± 41.1 | 0.012 |
| Cholesterol in mg/dL, total ± SD | 167.9 ± 47.8 | 164.6 ± 39.6 | 0.483 |
| Tumor stage | 0.110 | ||
| III | 136 (73.5) | 151 (66.2) | |
| IV | 49 (26.5) | 77 (33.8) | |
| Tumor site | 0.940 | ||
| Colon | 106 (57.9) | 130 (58.3) | |
| Rectum | 77 (42.1) | 93 (41.7) | |
| Histology | 0.001 | ||
| Adenocarcinoma | 177 (97.8) | 199 (89.6) | |
| Mucinous carcinoma | 4 (2.2) | 23 (10.4) | |
| Differentiation | 0.155 | ||
| Well differentiated | 13 (7.4) | 16 (7.8) | |
| Moderately differentiated | 148 (84.6) | 174 (84.5) | |
| Poorly differentiated | 14 (8.0) | 12 (5.8) | |
| Resection margin + | 3 (1.7) | 1 (0.6) | 0.371 |
| Lymphovascular invasion | 56 (25.9) | 76 (50.0) | 0.031 |
| MSI state | 0.670 | ||
| MSi | 78 (89.7) | 68 (90.7) | |
| MSI-low | 6 (6.9) | 6 (8.0) | |
| MSI-high | 3 (3.4) | 1 (1.3) | |
| Treatment modality | 0.160 | ||
| Resection only | 9 (4.9) | 20 (8.8) | |
| Resection + adjuvant chemotherapy | 115 (63.2) | 126 (55.3) | |
| Resection + chemoradiotherapy | 22 (12.1) | 24 (10.5) | |
| Neoadjuvant chemotherapy + resection | 17 (9.3) | 17 (7.5) | |
| Chemotherapy only | 17 (9.3) | 35 (15.4) | |
| Conservative care | 2 (1.1) | 6 (2.6) |
BMI: Body mass index; CEA: Carcinoembryonic antigen; CRC: Colorectal cancer; DM: Diabetes mellitus; MSI: Microsatellite instability.