VANCOUVER – It may be time to reconsider the criteria used to select obese patients with type 2 diabetes mellitus for bariatric surgery, according to data from a pooled cohort study.
Typically, diabetic patients are considered eligible only if they have a body mass index of at least 35 kg/m2 and poorly controlled glycemia, according to lead author Dr. Geltrude Mingrone, department of internal medicine, Catholic University, Rome, and department of diabetes and nutritional sciences, King’s College, London.
Dr. Geltrude Mingrone
But in her team’s new analysis of 727 patients, the best predictors of remission after bariatric surgery were a lower fasting glucose level, shorter diabetes duration at baseline, and having a gastric procedure with diversion, she reported at the World Diabetes Congress. And the best baseline predictors of improved glycemic control after bariatric surgery were lower waist circumference, better diabetes control, and lower triglyceride levels.
“We can say that there is a clear advantage of an early operation on diabetes remission that is independent of baseline body mass index. Baseline waist circumference and HOMA-IR [homeostasis model assessment of insulin resistance] are better predictors of glycemic control after bariatric surgery than body mass index,” Dr. Mingrone maintained.
“So I would like to advise the scientific community … to try to define new criteria for the selection of diabetic patients for metabolic surgery. Also, [it is important] because all over the world, the number of bariatric operations is only 250,000, a quarter of a million, while the potential eligible patients are many, many millions,” she concluded.
“I completely concur with Professor Mingrone – we need to come up with criteria for utilizing this procedure,” session comoderator Dr. Robert E. Ratner said in an interview.
“There are so many millions of individuals with diabetes, we cannot be doing surgery on all of them. We need to be selective, and we need to be very specific about why we are doing it and what we are looking for,” elaborated Dr. Rattner, who is a professor of medicine at Georgetown University and senior research scientist at the MedStar Health Research Institute, Washington, as well as chief scientific and medical officer of the American Diabetes Association, Alexandria, Va.
In the new research, the investigators merged databases of the Swedish Obese Subjects (SOS) prospective controlled study (N Engl J Med. 2004;351:2683-93) and two randomized, controlled trials conducted in Australia (JAMA. 2008;299:316-23) and Italy (N Engl J Med. 2012;366:1577-85).
Overall, 415 patients had bariatric surgery (about three-fourths had a gastric-only procedure, while the rest had a gastric procedure plus diversion) and 312 patients had medical management. The mean duration of diabetes at baseline was roughly 3.5 years.
After 2 years the proportion of patients achieving diabetes remission, defined as a fasting plasma glucose of less than 5.6 mmol/L in the absence of any antidiabetes medication, was higher in the surgical group than in the medical group (64% vs. 15%, P less than .001). And within the surgical group, it was higher for those whose operation included a diversion (76% vs. 60%, P = .016).
Among the patients who had surgery, the probability of remission fell with increasing baseline diabetes duration (–0.210), and fasting blood glucose level (–0.145), whereas it rose with increasing body mass index (+0.059). But when the type of surgery was added to the model, body mass index was no longer a significant predictor, and two additional predictors emerged: use of only oral antidiabetic medications versus none (–1.22) and receipt of a procedure with diversion (2.180).
In the subgroup who had a gastric-only procedure, the probability of remission fell with increasing diabetes duration (–0.197), and increasing fasting blood glucose level (–0.186), and it was lower for patients who used only oral antidiabetic medications (–1.364) or insulin with or without oral medications (–1.783). In the subgroup who had a gastric procedure with diversion, the only predictor was diabetes duration (–0.273).
Of note, there was no significant difference in the odds of remission between patients with a body mass index of 35 kg/m2 or lower and patients with a body index between 35 and 40 kg/m2.
Dr. Mingrone disclosed that she receives lecture fees and travel expenses from Novo Nordisk, and research grants from AstraZeneca, and is a consultant to Fractyl.