Can Bariatric Surgery Be A Cure For Type 2 Diabetes In Obese Patients?
Gastric restrictive procedures limit the capacity for food intake by creating a small pouch from the proximal stomach that limits the passage of solid foods (although liquids empty normally), and weight loss then progresses from a process of dietary re-education.1,9-11 A current example of such a procedure would be a laparoscopic gastric banding, which demonstrates a safety record and operative mortality now approaching zero in many large series in centers that perform large numbers of these procedures.
Malabsorption procedures, often utilized in conjunction with elements of gastric restriction, demonstrate greater weight loss outcomes than gastric restriction alone.12,13 Traditionally, however, these procedures demonstrate significantly higher long-term complication rates with patients exhibiting an increased incidence of protein and vitamin malabsorption syndromes, osteoporosis and liver failure.14,15
Consequently, these increased adverse outcomes created a stigma on bariatric surgical procedures that has persisted despite improved overall outcomes. Advances in surgical techniques, such as laparoscopy and postoperative micronutrient replacement therapies, have significantly reduced the overall risk for this type of procedure to less than 1 percent in experienced hands.16,17
What The Literature Says On The Efficacy Of Bariatric Surgery
While one should not lightly consider referring patients for possible bariatric surgery procedures, patients undergoing these types of bariatric procedures have reportedly had significant remission rates of their diabetes.18
One study demonstrated remission rates of 82.9 percent for 165 patients with type 2 diabetes for an average of 14 years following Roux-en-Y gastric bypass surgery.19 A meta-analysis of 22,094 patients showed that 84 percent of patients experienced complete reversal of type 2 diabetes following bariatric procedures with most stopping their oral medications or insulin injections before leaving the hospital.20
More recently, an article in the Journal of the American Medical Association (JAMA) focused on patients with diabetes who underwent gastric banding combined with conventional therapy (defined as lifestyle modification, increased physical activity and occasional medical therapy).21 Seventy-three percent demonstrated a remission of diabetes symptoms defined as normal blood sugar levels with no need to use supplemental insulin or oral hypoglycemic therapies. In contrast, only 13 percent of those individuals who received conventional therapy alone achieved remission of their diabetes.
There have been numerous proposed mechanisms of action to explain the observed remission rates of diabetes following bariatric surgery.22-27 Originally, researchers believed the improvement in diabetes symptoms was due simply to patient weight loss. However, more recent research has demonstrated that within a week of surgery, improved insulin sensitivity and blood glucose levels occur in patients with diabetes. This suggests that bariatric surgical intervention promotes a positive metabolic change prior to any actual weight loss.28,29
While the specific mechanism is elusive, one can conclude that following bariatric surgery, patients with diabetes benefit from both improved metabolic function as well as overall long-term weight loss.
Patient selection is of key importance in the determination of which patients may benefit from these types of bariatric procedures. Traditionally, bariatric surgery has been limited to those patients who are considered morbidly obese with a BMI of 40 kg/m2, or in patients with a BMI of >35 kg/m2 and one or more significant comorbid conditions.22
In patients with diabetes, there is a consensus that bariatric surgery should be reserved for those individuals with a BMI >35 kg/m2.29 In patients over 60 years or in children and adolescents, bariatric surgery is not recommended because long-term outcomes in these patient populations have not undergone extensive testing.