Weight loss induced by gastric banding improves insulin sensitivity and reduces secretory demand on β-cells in the Restoring Insulin Secretion (RISE) Consortium BetaFat Study. Here we examined the role of liver fat in this process. Total % body fat (%BF) was measured by DXA; visceral fat volume (VFV) and hepatic fat fraction (HFF) by MRI; and insulin sensitivity (steady-state glucose infusion rate/insulin [M/I]) and β-cell function (acute, steady state [SSCP] and arginine-stimulated maximum ([ACPRmax]) C-peptide concentrations by hyperglycemic clamp. Associations were assessed using linear regression models adjusted for age and sex. Baseline included 73 adults with moderate obesity and impaired glucose tolerance or early type 2 diabetes (81% female; mean±SD age of 49±10 years., BMI 35±3 kg/m2, %BF 44±6%, VFV 3.3±1.4 L and HFF 12±8%). At baseline, BMI and HFF were significantly associated with M/I (r=-0.27 and -0.33 respectively; p≤0.02) and SSCP (r=0.26 for each; p=0.02). Adjustment for M/I eliminated the significance of the associations with SSCP (r≤0.11 for each; p>0.3). %BF and VFV were not significantly associated with M/I or β-cell measures. During follow-up, 23 subjects from the gastric banding group repeated baseline tests at 2-years after surgery. BMI, %BF, VFV and HFF decreased by 3.7±2.9 kg/m2, 3.2±3.6%, 0.6±0.7 L, and 5.0±7.2% respectively during the 2-years follow-up (all p≤0.0003). Change in BMI was significantly associated with change in M/I (r=-0.42, p=0.049) but not with changes in β-cell measures. Change in HFF was significantly associated with changes in M/I (r=-0.59, p=0.003) and ACPRmax (r=0.55, p=0.007); adjustment for change in M/I reduced the association of HFF with ACPRmax to r=0.39 (p=0.06). Changes in %BF and VFV were not significantly associated with changes in M/I or β-cell measures. Thus, changes in hepatic fat may contribute to improved insulin sensitivity and reduced secretory demand on β-cells following gastric banding.
A. Xiang: None. J. Wu: None. T. Chow: None. M.P. Martinez: None. D.H. Hwang: None. E. Trigo: None. N. Katkhouda: Consultant; Self; Bard davol, Baxter, Medtronic, Storz. E. Beale: None. K.S. Nayak: None. T.A. Buchanan: Research Support; Self; Allergan, Apollo EndoSurgery.
National Institutes of Health; National Institute of Diabetes and Digestive and Kidney Diseases