Management of patients with type 2 diabetes before and after bariatric surgery: evolution and microvascular complications.

Bariatric surgery is increasingly seen as a treatment option for patient with type 2 diabetes (T2DM) and severe complex obesity (SCO). There is however no consensus on how to manage this cohort preoperatively and postoperatively. Patients with T2DM having cardiac surgery benefit from glycaemic optimisation prior to surgery. National Health Service Diabetes in the United Kingdom recommends that glucose is optimised prior to all elective surgery. However, bariatric surgery such as gastric bypass (RYGB) is distinct from general surgery. Glycaemic control improves immediately after RYGB and thus all T2DM patients need a review of their glucose lowering medications postoperatively. Preoperatively most bariatric centres use a low calorie diet (LCD) which improved glycaemic control and may predisposed patients using insulin or sulphonylureas to risks of hypoglycaemia. There are no protocols and consensus among bariatric centres on how best to manage patients with T2DM preoperatively and postoperatively. Moreover patients with difficult to control T2DM are at risk of microvascular complications of diabetes. So far, there is little evidence on the impact of bariatric surgery on diabetes nephropathy, retinopathy and neuropathy. In conclusion, bariatric surgery improves glycaemic control; however, there are limited studies, and no guidelines on how to manage patients with T2DM pre and postoperatively. Given the increasing proportion of T2DM patients referred for bariatric surgery, there is a need to review current practice on how to manage these patients in the short term and long term with a specific focus on improving end organ damage such as retinopathy, neuropathy and nephropathy.