Introduction: A reliable predictive indicator for the course of critically ill patients' conditions is lactate. Metformin users have increased lactate levels at ICU admission without a concurrent rise in mortality, according to a number of small studies. In a wide range of patient populations, elevated lactate has been linked to greater mortality. The purpose of this study was to evaluate lactate levels and compare 30 days mortality in intensive caredunit patients who had and had not previously received metformin medication. Material and Method: This study included patients admitted in intensive care units of Assam medical college between June 2021 to May 2022 with at least one blood lactate level between 12 hr. before until 6 hr after ICU admission. The statistical analysis of the data was done with Microsoft Excel 2010 and the statistical package for social sciences, SPSS for Windows, version 20.0. Chicago: SPSS Inc. Results: The mean lactate in survivors was 3.05 mmol/L with a standard deviation of 2.41 and was lower than that in non-survivors, where it was 4.01 mmol/L with a standard deviation of 2.39. Non-survivors had a higher distribution of lactate levels than do survivors. Since the pvalue was 0.001, which was highly significant, it may be concluded that lactate levels and survival were related. Metformin was used by both 64% of survivors and 30% of non-survivors. 36% of those who did not take metformin lived, compared to 70% of users. The use of metformin and survival were significantly correlated, as shown by the p-value of 0.001, which was highly significant. Conclusion: Lactate concentrations were significantly correlated with mortality in this observational study. Early lactate levels were an important predictor of mortality in critically ill patients admitted to the intensive care unit, and higher preadmission metformin use in survivors demonstrated metformin's important contribution to higher survival rates.