Protocol B-Intensive management: On admission to hospital all pre-operative oral antidiabetic agents and insulin are stopped and glucose monitoring is carried out every four hours at the same time as routine observations. Actrapid insulin is administered as per standard sliding scales (appendix A). Just prior to discharge, total insulin administered over the previous 24 hour post-operative period is calculated. Based on the results of ward based glucose monitoring patients are discharged home on metformin 1000mg BID and/or the equivalent amount of Glargine insulin requirement in previous 24 hours prior to discharge. These patients are also advised to continue glucose monitoring at home and will be contacted every day and their medication adjusted to maintain a fasting glucose between 5 and 7mmol/l. When this is consistently achieved the investigators will stop calling, but patients will be encouraged to continue monitoring their blood sugars and contact the investigators should they experience any problems with their glycaemic control.