Aim: The aim of this study is to construct a new tool for the assessment of sexual dysfunction among men with diabetes that is valid and reliable across different ethnicities, languages and socio-economic backgrounds in South East Asia. Methods: Focus group interviews were conducted to determine the construct of the questionnaire. Content and face validity were assessed by a panel of experts. A pilot study was conducted to validate the Sexual Dysfunction in Asian Men with Diabetes (SAD-MEN) questionnaire in English and Malay. The International Index of Erectile Function-5 (IIEF-5) was used for comparison. Construct validity was assessed using exploratory factor analysis, reliability was determined using Cronbach's α (> 0.700), and test-retest reliability using Spearman's rank correlation coefficient. Results: The SAD-MEN questionnaire yielded moderate face and content validity, with high reliability as shown by Cronbach's α values of 0.949 for sexual performance and 0.775 for sexual desire for the English version. The Malay language questionnaire had a Cronbach's α value of 0.945 for sexual performance and 0.750 for sexual desire. Test-retest reliability using Spearman's test gave correlation coefficients of r = 0.853, P = 0.000 for the English language questionnaire and r = 0.908, P = 0.000 for the Malay language questionnaire. Conclusion: The SAD-MEN questionnaire is a valid and reliable tool by which to assess sexual dysfunction in English- and Malay-speaking Malaysian and South East Asian men with diabetes.