Bariatric Surgery for Type 2 Diabetes Reversal: The Risks

The twin epidemics of obesity and type 2 diabetes are on the rise. From 1986 to 2000, the prevalence of BMI 30 kg/m doubled, whereas that of BMI .40 kg/m quadrupled, and even extreme obesity of BMI 50 kg/m increased fivefold (1). Of particular concern is the alarming increasing prevalence of obesity among children, suggesting that the epidemic will worsen (2). The impact of obesity on longevity has been well documented. In the world, over 2.5 million deaths annually can be attributed to obesity; in the U.S. alone over 400,000 deaths attributable to obesity occur per year— second only to those attributable to cigarette smoking. There is a direct relationship between increasing BMI and relative risk of dying prematurely, as evidenced in the Nurses’Health Study with a 100% increase in relative risk as BMI increased from 19 to 32 kg/m. Annual risk of death can be as high as 40-fold that of an ageand sex-matched nonobese cohort (3,4). The Framingham data revealed that for each pound gained between ages 30 and 42 years there was a 1% increased mortality within 26 years, and for each pound gained thereafter there was a 2% increased mortality. Only one in seven obese individuals will reach the U.S. life expectancy of 76.9 years. In the morbidly obese population, average life expectancy is reduced by 9 years in women and by 12 years in men. It has been over 10 years since the resolution of type 2 diabetes was observed as an additional outcome of surgical treatment ofmorbid obesity.Moreover, it has been shown unequivocally that diabetes-related morbidity and mortality have declined significantly postoperatively, and this improvement in diabetes control is long lasting. Bypass procedures, the Roux-en-Y gastric bypass (RYGBP) and the biliopancreatic diversion (BPD), are more effective treatments for diabetes than other procedures and are followed by normalization of concentrations of plasma glucose, insulin, and HbA1c in 80–100% of morbidly obese patients. Studies have shown that return to euglycemia and normal insulin levels occurs within days after surgery, long before any significant weight loss takes place. This fact suggests that weight loss alone is not a sufficient explanation for this improvement. Other possible mechanisms effective in this phenomenon are decreased food intake, partial malabsorption of nutrients, and anatomical alteration of the gastrointestinal (GI) tract, which incites changes in the incretin system, affecting, in turn, glucose balance. Better understanding of those mechanisms may bring about a discovery of new treatment modalities for diabetes and obesity. Lifestyle intervention programs with diet therapy, behavior modification, exercise programs, and pharmacotherapy are widely used in various combinations to treat obesity. Unfortunately, with extremely rare exceptions, clinically significant weight loss is generally very modest and transient, particularly in patients with severe obesity (5,6). The failure rate for those programs is around 95% at 1 year. There is a great interest in the mortality and morbidity associated with bariatric surgery in the medical community, in the media and, understandably, in the minds of morbidly obese patients. In part, this interest is due to the universal appreciation of the consequences of the global obesity epidemic, the growing recognition that bariatric surgery is currently the most effective therapy for the disease of morbid obesity, and that the increasing numbers of bariatric procedures have reached over 200,000 annually in the U.S. and half a million annually worldwide (5). Yet, because there is still reluctance to accept obesity, and even morbid obesity, as a disease entity, the surgery for this problem and its operative mortality are not well accepted by the medical and lay communities. Per the 1991 National Institutes of Health Consensus Conference Guidelines, patients are considered as surgical candidates only if their BMI is $40 kg/m, or if their BMI is .35 kg/m and they suffer from other life-threatening comorbidities such as type 2 diabetes, hypertension, and cardiovascular disease.