Background: Insulin resistance (IR) in pancreatic cancer (PC) patients is associated with cachexia and poor outcome. Pioglitazone (PIO) improves insulin sensitivity via activation of peroxisome proliferator-activated receptor (PPAR gamma). Effects of PIO on insulin sensitivity, glucose homeostasis, and circulating adipokine levels in PC have not been examined. Methods: Patients with metastatic PC were administered PIO 45mg/day orally for 8 weeks concurrent with chemotherapy. Patients with known DM at enrollment were identified Fasting plasma was collected at baseline, weeks 2, 4, 6, 8 of pioglitazone treatment and at 2 weeks-post treatment. The primary objective was to describe changes in indicators of IR, including glucoregulatory hormone levels, glucose tolerance, and inflammatory cytokines. Results: Fourteen patients (age 64y), with a mean BMI of 28 were enrolled. Mean adiponectin increased from baseline to week 8 of treatment (14.2± 3.3 and 46.9±11.4µg/ml, respectively, P ≤ 0.01), and returned to baseline levels at 2 weeks post-treatment (15.1±1.9 µg/ml). Markers of IR (serum glucose, insulin, glucagon, and response to an oral glucose bolus) did not correlate with tumor size, inflammatory cytokine levels, GM-CSF, or CA19-9. A dichotomous response to PIO treatment was observed between non-diabetic and T2DM patients. Fasting insulin increased 70.6±31.3% from baseline to treatment week 8 in patients with T2DM. In contrast, treatment of non-diabetic patients decreased fasting insulin by 40.2±6.3%, demonstrating a significant, P ≤ 0.01, difference in treatment response between PC patients with or without T2DM. Conclusions: We have demonstrated that PC patients respond to 8 weeks of PIO treatment with a significant rise in the insulin sensitizing adipokine, Adiponectin, with a complete wash-out after 2 weeks of cessation. PIO results in opposing fasting insulin responses in non-diabetic and DM patients suggests that diabetes status plays a significant role in the glucoregulatory effects of PIO treatment in PC patients. Clinical trial information: NCT01838317