Background: Glucose and other metabolites (lactates and glutamine) in the tumor microenvironment (TME) may alter the activity of the immune system cells. Cancer cells consume glucose and its decrease in the TME affects the function of tumour-infiltrating lymphocytes (TILs). Moreover, tumor-infiltrated immunosuppressive cells and vascular endothelial cells also deplete nutrients, in the TME, enhancing an immunosuppressive environment. On the basis of the results coming from our previous works regarding lymphocytes to monocytes ratio (LMr) and diabetes, suggesting a role for each of them as predictors of better outcomes, in this study we evaluate both of them in order to establish a possible role of them as outcomes predictive factors. Methods: Data from 228 patients (pts) were collected retrospectively from 2016 to 2021: 175 from the Medical Oncology Unit of University Hospital of Cagliari; 53 from the Medical Oncology Unit, AOU Ospedali Riuniti di Ancona. All pts had stage IV disease and received gemcitabine plus nab-paclitaxel 1st line chemotherapy. Statistical analysis was performed with the MedCalc package. We aimed to evaluate the correlation between treated DM2 and lymphocytes to monocytes ratio (LMr) ≥ 4 with outcomes. Survival distribution was assessed by Kaplan-Meier curves. Multivariate analysis was performed taking into consideration the following prognostic factors: sex, ECOG-PS, LMr, NLr, LDH, Ca19.9, and metastatic sites. Results: Median age was 68 (±9), 123/228 (54%) were male, 94/232 (40,6%) were affected by DM2 (insulin or metfomin-treated) and 138 (59,4%) pts were not affected by DM2. 52/228 (23%) pts had a LMr ≥ 4, 176/228 (77%) pts had a LMr < 4. In multivariate analysis, DM2 and LM ratio ≥ 4 were found to be independent factors associated with higher overall survival. Therefore, we divided the pts into 3 groups: co-presence DM2 and LM ≥ 4 (DM+LM+); absence of DM2 and LM ≥ 4 (DM-LM-); presence of DM2 or LM ≥ 4 (DM+LM- or DM-LM+). DM+LM+ demonstrated statistically significantly higher median OS than DM+LM-/DM-LM+ and DM-LM- (not reached versus 21 versus 9 months, respectively, p < 0.0001). Furthermore, DM+LM+ showed a statistically significant better median PFS than DM+LM-/DM-LM+ and DM-LM- (11 versus 9 versus 6 months, respectively, p = 0,0036). Conclusions: Results showed a correlation between pts with DM2/LMr ≥ 4 and better outcomes. This may suggest the presence of a link between glucose metabolism and lymphocytes activation. Antidiabetic medications could promote the inhibition of Warburg effect in tumor cells, and, consequently, provide a better glucose intake to extracellular microenvironment, and immune cells, including T lymphocytes. This process leads to a higher activity of T-cells and a better treatment response. Further studies are warranted.