Mice with Vhlh loss in ß-cells exhibit glucose intolerance [2], [3], [4], and the reduced expression of maturity markers led us to hypothesize that the perinatal lethality observed in Pdx-1-Creearly;VhlhLoxP/LoxP mice might result from perturbed glucose homeostasis due to compromised cellular function. The gene discussed is PDX1; the disease is Glucose intolerance.