Post-COVID syndrome, also known as long COVID, includes a range of symptoms that persist for months or even years after initial infection such as fatigue, shortness of breath, joint pain, chest pain, muscle aches, and heart palpitations, among others. In addition, long COVID is related with new-onset diseases such as diabetes mellitus. The association between SARS-CoV-2 infections and the development of diabetes mellitus is complex and not fully understood. Therefore, the objective of this article was to summarize the state of the art in possible mechanisms involved in the development of diabetes mellitus in the post-COVID-19 era, particularly the impact of SARS-CoV-2 variants on molecular mimicry, the role of viral m6A RNA methylation, and the potential associations between these factors. A better understanding of the combinatorial effects of these mechanisms is paramount for both clinicians and researchers alike because it could help tailor more effective treatment strategies, enhance patient care, and guide future research efforts.