Univariate logistic regression analysis of factors associated with vitamin B12 deficiency
| Variables | OR (95% CI) | P value |
| Age | 1.034 (0.996 to 1.074) | 0.077 |
| Gender | 1.093 (0.498 to 2.396) | 0.825 |
| BMI | 0.967 (0.786 to 1.190) | 0.753 |
| Hypertension | 3.268 (1.068 to 10.000) | 0.038 |
| Duration of diabetes | 1.047 (0.989 to 1.108) | 0.115 |
| Duration of metformin use | 1.043 (0.985 to 1.103) | 0.147 |
| Long-term use of metformin (duration > median duration) | 8.539 (2.459 to 29.648) | < 0.001 |
| Metformin dose | 1.002 (1.001 to 1.003) | 0.002 |
| Metformin dose > median dose | 4.942 (1.777 to 13.749) | 0.002 |
| Hb | 0.949 (0.744 to 1.210) | 0.671 |
| MCV | 1.068 (0.993 to 1.148) | 0.075 |
| Fasting plasma glucose | 0.995 (0.988 to 1.003) | 0.210 |
| HbA1c | 0.733 (0.557 to 0.964) | 0.026 |
| MUI | 1.043 (1.009 to 1.078) | 0.014 |
| MUI≥10 | 5.095 (1.459 to 17.788) | 0.011 |
BMI, body mass index; Hb, haemoglobin; MCV, mean cell volume; MUI, metformin usage index.