Background. Obstructive sleep apnoea (OSA) is related to type 2 diabetes (T2DM), and it may be associated with reduced inspiratory muscle strength (IMS). The aim of this study was to investigate the IMS in patients with T2DM, with or without OSA. Methods. Patients with T2DM with OSA (n=33) and without OSA (n=28) were included. The maximum IMS was tested using the POWER breathe KH2 device. Reference IMS values were data calculated using an algorithm based on general populations and adjusted for age and gender. Results. There was no difference in IMS between the OSA group (median (range) 77 (35-124) cmH2O) and the non-OSA group (84 (33-122) cmH2O) (p=0.97). The IMS values were reduced in the OSA group compared with the reference values (92.9 (62.3-100.0) cmH2O) (p=0.030), whereas the non-OSA group did not have reduced IMS. When the IMS values of all T2DM patients were compared with reference values, the IMS values were 79 (33-124) cmH2O and 93.8 (62.3-102.4) cmH2O, respectively (p=0.017). Conclusion. No difference in IMS between patients with T2DM with or without OSA was found. However, patients with T2DM and OSA had reduced IMS compared with age- and gender-matched references whereas the non-OSA group did not have reduced IMS.