SPTLC1 and diabetes mellitus: Similarly, the increased levels of HOMA-IR in the total obese and obese-DM groups was significant compared to the control cohort and obese-NDM groups, respectively (P < 0.005 and P < 0.005, respectively), as shown in Fig. 3C. Correlation analysis was performed to assess whether SPT1 mRNA expression was associated with ceramide levels and HOMA-IR.