The CRF statistician will be blinded to the group randomisation allocation for the purposes of analysis. The investigators will compare MAGE, time spent in hypoglycaemia (hours/day), and Clarke scores in those with and without severe insulin deficiency using unpaired T-tests. The investigators will compare response to DPPIV inhibitor (incremental area under the curve glucose with mixed meal test with vildagliptin - incremental area under the curve glucose test without vildagliptin) between groups using unpaired T tests. The investigators will assess whether each outcome variable is normally distributed prior to analysis and log transform or use equivalent non-parametric analysis where necessary.