Mr Ahmed Ahmed, Consultant GI and Bariatric Surgeon at Cromwell Hospital, explains the impact of bariatric surgery on the improvement or resolution of Type 2 Diabetes (T2D). 


Obesity and T2D are closely related and represent significant public health issues worldwide, thus the term “diabesity” was created to emphasize the close association between the above problems. T2D prevalence is increasing globally in parallel with obesity, and as many as 23 % of patients with morbid obesity have T2D, whereas approximately 50 % of those diagnosed with T2D are obese. Uncontrolled diabetes can cause macrovascular and microvascular complications, including myocardial infarction, stroke, vision loss, neuropathy and renal failure. 

Obesity and T2D are difficult to control by current medical treatments, including diet, drug therapy and behavioural modification. Bariatric surgery is the most effective treatment of morbid obesity and is also very effective in the resolution of type 2 diabetes. This effect occurs even before the start of weight loss. The mechanisms underlying this are currently under study.  

Weight loss, achieved through reduction of energy intake and increased exercise is the foundation of treatment for T2D. According to the Look AHEAD trial, sustained weight loss via lifestyle modification results in improvement of diabetic control, but this is difficult to achieve and maintain over time. Medications to reduce hyperglycaemia and cardiovascular risk play an important role, but only up to 10 % of patients with T2D manage to improve long term risk of complications. The SOS study showed that patients after bariatric surgery had greater mean weight loss, reduced incidence of T2D, and less mortality than obesity-matched control patients. Randomized clinical trials evaluating bariatric surgery as treatment for T2D have shown that bariatric surgery produced more weight loss and better glycaemic control than typical medical therapy.   

 Further research:  

According to Mingrone et al, after 2 years, diabetes remission had occurred in 75 % of patients undergoing gastric bypass, whereas no remission of diabetes was reported for the patients who received medical therapy.  

According to the results of the recent STAMPEDE trial, after 3 years, 38 % of patients undergoing gastric bypass achieved glycaemic control with HbA1c < 6.0 % or less, compared to 24 % of patients undergoing laparoscopic sleeve gastrectomy and 5 % of patients who received intensive medical therapy.  

A recent meta-analysis of the current RCT data available literature, published in BMJ, compared surgery with non-surgical treatment for obesity and concluded that at two years, bariatric surgery leads to greater weight loss and higher remission rates of T2D. All studies related to the impact of bariatric surgery on the improvement or resolution of T2D demonstrated significant results in favour of the surgical intervention.  

The International Diabetes Federation has recommended bariatric surgery to treat diabetes since 2011.  The IDF suggested that people with a BMI between 30-35 kg/m2 with uncontrolled diabetes (A1c >7.5%) be “eligible for surgery” and those with a BMI between 35-40 kg/m2 be “prioritized for surgery.” 

Therefore, the surgical treatment of diabetes is highly effective and should be considered and offered by all who suffer from the condition.