INS and Glucose intolerance: To understand the cause of the observed hyperglycemia and glucose intolerance, we next assessed, using immunocytochemistry (Figure 2A), insulin expression in β-cells (mean intensity of insulin staining; Figure 2B), the ratio of β-cells/α-cells (Figure 2C), and β-cell mass (Figure 2D) as determined from the percentage of the pancreatic surface occupied by insulin-positive structures.