Chronic low-grade inflammation plays a key role in the pathogenesis of type 2 diabetes mellitus (T2DM) and its vascular complications. Hematological indices derived from routine blood counts, such as neutrophil-to-lymphocyte ratio (NLR), derived neutrophil-to-lymphocyte ratio (dNLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR), systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), and aggregate index of systemic inflammation (AISI), have been proposed as surrogate markers for systemic inflammation and predictors of cardiovascular risk. This study aimed to evaluate the predictive value of these inflammatory indices concerning the presence of micro- and macrovascular complications and cardiovascular mortality in patients with type 2 diabetes mellitus. We conducted a retrospective cohort study including 237 patients with T2DM. We assessed the association between hematological indices and cardiovascular mortality, followed by a ROC curve analysis to evaluate their predictive performance, and a multiple logistic regression. Thirty patients (12.66%) died during the study period. ROC analysis showed that SIRI (AUC = 0.680 [95% CI 0.576-0.779]), LMR (AUC = 0.667 [95% CI 0.564-0.763]), AISI (AUC = 0.662 [95% CI 0.553-0.768]), and NLR (AUC = 0.657 [95% CI 0.545-0.764]) had the best discriminative capacity, all with specificity >70%. The relation remained significant even after adjustments for confounding variables in multiple logistic regression. For microvascular complications, Monocyte count (AUC = 0.611 [95% CI 0.532-0.69]) and LMR (AUC = 0.608 [95% CI 0.521-0.695]) showed minimal but notable predictive value. SIRI, LMR, AISI, and NLR were significantly associated with mortality and demonstrated modest discriminative ability. These markers, accessible and cost-effective, may be useful tools for risk stratification in T2DM patients. Further validation in prospective cohorts is warranted.