Nutritional care of bariatric/metabolic surgery for the treatment of type 2 diabetes mellitus

Bariatric/metabolic surgery (BMS) is highly effective in treating obese associated type 2 diabetes mellitus (T2DM) and a commonly performed surgical procedure worldwide now. However, vitamin D, calcium and iron deficiencies are commonly presented in obese patients before operation because of reduced bioavailability and poor dietary intake. These un-recognized or under-treated nutritional deficiencies might lead to devastating complications of bone, immune function, neurologic and muscular systems. Therefore, the benefit of BMS may be tempered by the associated post-operative nutritional deficiencies. Pre-operative nutritional screening and treatment thus are essential for BMS patients. The pre-operative existing nutritional deficiencies might be exacerbated after BMS due to reduced absorption, poor dietary intake and compliance with postoperative supplement instructions. Protein deficiency is the most commonly met macronutrient deficiencies after BMS. Iron, calcium and vitamin D deficiencies are commonly met micronutrient deficiencies after BMS and may bring significant clinical problems to the patients. Some micro-nutrient deficiencies, such as copper, selenium and zinc, are difficult to diagnose because difficult in assessment and frequently confounded by deficiencies in other nutrients. Therefore, post-operative nutritional supplements following established recommendations are essential for patients received BMS. In addition, all the patients should receive regular follow-up by a multidisciplinary team for the prevention and treatment of nutritional deficiencies in order to optimize the outcomes of BMS.