SLC30A8 and Impaired glucose tolerance: Consistent with impaired β-cell function in the absence of ZnT8, we (15, 17) and others (18) have previously shown, using CreLoxP technology, that inactivation of the Slc30a8 gene in mice, either systemically (15, 17, 18) or selectively in the β-cell (19), leads to abnormal insulin release in vivo and impaired glucose tolerance.