INS and diabetes mellitus: RYGB prevented hyperglycemia in 100% of HFD-fed NZO mice (Fig 4b), suggesting that HFD accelerates the development of overt diabetes, which can be prevented by RYGB, and RYGB, but not SHAM-PF, preserves insulin+ cells, contributing to improved hyperglycemia in HFD-fed NZO mice.