GCG and Glucose intolerance: Figure 1 shows that glucose intolerance was characterised by a delayed insulin secretion, but only those with CFRD had a diminished overall insulin secretion (Figure 1B). Time to peak for the proinsulin appearance was less affected by glucose tolerance, however proinsulin secretion was highest in those with IGT (Figure 1C). The figure also shows comparable peak glucagon concentration over the first 30 minutes post-glucose ingestion (Figure 1D), but increasing time to glucagon nadir with worsening glucose tolerance (CMin) (Supplementary Figure 1).