AbstractType 2 diabetes (T2D) is a global pandemic. Currently, the drugs used to treat T2D improve hyperglycemic symptom of the disease but the underlying mechanism causing the high blood glucose levels have not been fully resolved. Recently published data showed that salt form of niclosamide improved glucose metabolism in high fat fed mice via mitochondrial uncoupling. However, based on our previous work we hypothesised that niclosamide might also improve glucose metabolism via inhibition of the glucagon signalling in liver in vivo. In this study, mice were fed either a chow or high fat diet containing two different formulations of niclosamide (niclosamide ethanolamine salt - NENS or niclosamide - Nic) for 10 weeks. We identified both forms of niclosamide significantly improved whole body glucose metabolism without altering total body weight or body composition, energy expenditure or insulin secretion or sensitivity. Our study provides evidence that inhibition of the glucagon signalling pathway contributes to the beneficial effects of niclosamide (NENS or Nic) on whole body glucose metabolism. In conclusion, our results suggest that the niclosamide could be a useful adjunctive therapeutic strategy to treat T2D, as hepatic glucose output is elevated in people with T2D and current drugs do not redress this adequately.