Chronic stress may facilitate the development of metabolic disorders including insulin resistance (IR) and type 2 diabetes mellitus (T2DM). MiR-18a and miR-34c modulate central cell responsiveness to stress by targeting glucocorticoid receptor (GR) and corticotropin-releasing factor receptor type 1 (CRFR1) mRNA, which are important regulators of the hypothalamus-pituitary-adrenal (HPA) axis. This study explored the relationship between T2DM/IR and expression of miR-18a and miR-34c in peripheral blood mononuclear cells (PBMCs) in an occupational sample. Three groups of study subjects were involved, including T2DM patients, impaired fasting glucose (IFG) individuals and healthy controls. The degree of IR was determined using the homoeostasis model assessment of insulin resistance (HOMA-IR). The expression of miR-18a and miR-34c in PBMCs was evaluated by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Expression levels of miR-18a and miR-34c were significantly correlated with cortisol, corticotropin-releasing factor (CRF) and interleukin 6 (IL-6) (P < 0.05). The increased levels of miR-18a were associated with risk of T2DM (adjusted OR = 1.48, 95% CI: 1.25-1.75, P < 0.001) and IFG (adjusted OR = 1.33, 95% CI: 1.09-1.63, P = 0.005). By contrast, the decreased levels of miR-34c were associated with risk of T2DM (adjusted OR = 0.81, 95% CI: 0.75-0.88, P < 0.001) and IFG (adjusted OR = 0.87, 95% CI: 0.81-0.94, P < 0.001). After adjusting for potential confounders, miR-18a and miR-34c were independent positive and negative predictors of HOMA-IR, respectively (P < 0.001). The miRNA panel with the two miRNAs demonstrated high accuracy in the diagnosis of T2DM (AUC = 0.851, 95% CI: 0.786-0.800, P < 0.001). MiR-18a and miR-34c in PBMCs may be important marker of stress reaction and may play a role in vulnerability to T2DM as well as IR.