CTSD and metabolic dysfunction-associated steatotic liver disease: Likewise, plasma CTSD levels have been previously correlated with insulin resistance in newly diagnosed type 2 diabetes (12) and two large community cohorts without diabetes (with more than 70% of participants being healthy residents) (13) and were even implicated as non-invasive markers for different stages of NAFLD, a metabolic condition linked to type 2 diabetes (10, 14).