Reduced insulin clearance differently relates to increased liver lipid content and worse glycemic control in recent-onset type 2 and type 1 diabetes mellitus
Objective: Diabetes mellitus may feature impaired insulin kinetics, which could be aggravated by altered hepatic metabolism and glycemic control. Thus, we examined insulin clearance and its possible determinants in persons with recent-onset diabetes. Research design and methods: Participants of the German Diabetes Study (GDS) with type 1 diabetes (T1D; n=306), type 2 diabetes (T2D; n=489) or normal glucose tolerance (CON; n=167) underwent hyperinsulinemic-euglycemic clamps to assess whole-body insulin sensitivity (M-value) and insulin clearance (ICCLAMP). Insulin clearance rates were further calculated during intravenous glucose (ICIVGTT) and mixed meal tolerance tests (ICMMT). Hepatocellular lipid content (HCL) was quantified by 1H-magnetic resonance spectroscopy. Results: Both T1D and T2D had lower ICCLAMP (0.12±0.07 and 0.21±0.06 vs. 0.28±0.14, all p<0.05) and ICMMT than CON (0.71±0.35 and 0.99±0.33 vs. 1.20±0.36, all p<0.05). In T1D, ICCLAMP, ICIVGTT, ICMMT correlated negatively with HbA1c (all p<0.05). M-value correlated positively with ICIVGTT in CON and T2D (r=0.199 and r=0.178, p<0.05) and with ICMMT in CON (r=0.176, p<0.05). HCL negatively associated with ICIVGTT and ICMMT in T2D (r=-0.005 and r=-0.037) and CON (r=-0.127 and r=-0.058, all p<0.05). In line, T2D or CON with steatosis featured lower ICMMT than those without steatosis (both p<0.05). Conclusions: Insulin clearance is reduced in both type 1 and type 2 diabetes already within the first year after diagnosis, but correlates negatively with liver lipid content rather in type 2 diabetes. Moreover, insulin clearance differently associates with glycemic control and insulin sensitivity may suggest specific mechanisms affecting insulin kinetics.