Mitochondrial gene expression in visceral (VAT) and lipogenesis in abdominal subcutaneous adipose tissue (SAT) are lower in insulin resistance (IR). Humans with hormone sensitive lipase (HSL) gene mutations are prone to type 2 diabetes (T2D). SAT is divided into deep (DSAT) and superficial SAT (SSAT). SSAT was speculated to be protective in T2D, but gender specificity is unknown. We hypothesized lower mitochondrial efficiency as well as lower markers of lipogenesis and lipolysis in SSAT only in male T2D patients vs. glucose-tolerant humans (CON), which may characterize dysfunctional SSAT. In 20 T2D and 20 CON matched for sex, BMI and age (female/male: 6/14 per group; 32±1 vs. 31±1 kg/m2, 52±2 vs. 54±2 years), we assessed M-values by euglycemic-hyperinsulinemic clamps, liver fat content (HCL) and VAT by MRS. In biopsies of SSAT, mitochondrial oxidative capacity was measured by respirometry, lipogenesis assessed from stearoyl-CoA desaturase (SCD) mRNA, lipolysis from adipocyte triglyceride lipase (ATGL) and HSL mRNA by RTqPCR. The insulin resistant T2D had 63% and 22% higher HCL (p<0.01) and VAT (p<0.05) than CON. In SSAT, T2D featured 20%, 50%, 70%, 49% reductions in oxidative capacity, SCD, ATGL and HSL mRNA (all p<0.05). Gender segregated analyzes showed higher oxidative capacity only in females, whereas only ATGL was also lower in female T2D vs. CON. In T2D, VAT was 22% lower (p<0.01) and HSL mRNA 70% higher (both p<0.001) in female than in male participants.
In conclusion, lower lipogenesis and lipolysis in SSAT of male T2D patients may lead to inadequate lipid storage in SSAT, thereby promoting ectopic fat storage as HCL and VAT.
K. Bódis: None. J. Lundbom: None. T. Jelenik: None. D.F. Markgraf: None. A. Strom: None. O.P. Zaharia: None. Y. Karusheva: None. V. Burkart: None. K. Müssig: None. Y. Kupriyanova: None. M. Ouni: None. J. Hwang: None. D. Ziegler: None. A. Schuermann: None. M. Roden: Speaker's Bureau; Self; Boehringer Ingelheim GmbH. Research Support; Self; Boehringer Ingelheim GmbH. Consultant; Self; Poxel SA. Research Support; Self; Danone Nutricia Early Life Nutrition, GlaxoSmithKline plc., Nutricia Advanced Medical Nutrition, Sanofi. J. Szendroedi: None.