Impairments in glucose tolerance and a tendency toward impaired β-cell function apparent in vivo in female βVps13cKO mice might reflect abnormal glucose- or depolarization-dependent insulin secretion from β-cells. To investigate this, we studied insulin release from batches of islets from mice 20–23 wk old, as shown in Fig. 8. Interestingly, both glucose (16.7 mM) and KCl (20 mM) -stimulated secretion tended to increase in βVps13cKO vs. control islets from males fed either RC (Fig. 8A) or HFD (Fig. 8B). Whereas a similar tendency was also apparent for islets from females maintained on a HFD (Fig. 8D), those from female βVps13cKO mice fed RC showed no change in insulin secretion vs. controls (Fig. 8C) when stimulated with 20 mM KCl. No differences between HFD-fed control and βVps13cKO mice were seen when the same experiment was conducted under perifusion (Fig. 8E).