Optimizing Diabetes Outcomes from Weight Loss Surgery: The First Year May Matter Most

Weight fluctuations after year one less important than percentage of weight loss in year one, study suggests

A recent subanalysis of the STAMPEDE trial found that weight loss in the first year may be more important for diabetes control than weight regain after the first year in patients with type 2 diabetes mellitus (T2DM).

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“Patients who undergo bariatric surgery often lose the majority of their weight the first year,” notes Cleveland Clinic endocrinologist Sangeeta Kashyap, MD. “Some may experience weight fluctuations following surgery, with periods of significant weight loss followed by weight regain. We were surprised to find that, after the first year, weight fluctuations don’t seem to matter in diabetes management. It seems more important for patients to lose a maximum amount of weight in that first year.”

Metabolic surgery supersedes medical intervention for T2DM patients

Metabolic surgery is a weight loss procedure that is more effective than medical interventions, producing increased glycemic control and cardiometabolic health benefits. Recent studies indicate a correlation between weight lost during the first and second years following surgery and greater improvements in glycosylated hemoglobin (HbA1c). Prior to this study, little was known about the relationships between weight loss and regain following surgery and glycemic control.

In the STAMPEDE trial, 150 patients with T2DM and obesity were randomized to bariatric surgery, and 96 of them had five-year follow-up. Forty-nine patients had Roux-en-Y gastric bypass (RYGB) surgery and 47 had sleeve gastrectomy (SG).

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Less initial weight loss correlates with higher HbA1C levels five years out

In the first year following surgery, patients who had RYGB lost 27.2 percent of their baseline weight and patients who had SG lost 25.1 percent from baseline. After year one, weight regain was similar in both surgery groups (RYGB regained 8.2 percent and SG regained 9.4 percent). Analysis indicates that, regardless of surgery type, less weight loss in the first year positively correlated with higher five-year HbA1c.

In SG only, weight gain from nadir positively correlated with increased HbA1c levels. One reason for this discrepancy may be the mechanism of glycemic control brought about by RYGB compared to SG. In RYGB, increased GLP-1, changes in bile acids, as well as intestinal hypertrophy and hyperplasia induce improvements in glycemic control. This may partially explain why improvements in glycemic control were less weight loss dependent in RYGB than in SG.

Less percent weight loss in year one was positively correlated with a greater diabetes incidence at five years. Similarly, reduced weight loss in the first year also positively correlated to increased triglycerides at five years, but there was no association with systolic blood pressure.

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Weight fluctuations less important than optimizing initial weight loss

“This study could really change the way we look at surgical weight loss for diabetes management. A lot of research has been undertaken in the last several years to identify which weight loss procedure is best, and ways to minimize weight fluctuations after surgery,” Dr. Kashyap says. “Our data indicate that what happens after year one may not be as important as optimizing weight loss that first year.”

Future studies will examine medical interventions to maximize weight loss and manage diabetes in patients following weight loss surgeries, as well as the longer term (beyond five years) impact of weight change trajectory on diabetes management.