NNT, a mitochondrial enzyme that catalyzes the reversible transfer of reducing equivalents from NADH to NADP [26], has been considered as a plausible genetic change to explain glucose intolerance and defective insulin secretion observed in JJ mice [12], which harbor a spontaneous in-frame 5-exon deletion in the NNT gene with a complete loss of the protein [12,27]. Here, INS is linked to Glucose intolerance.