1. Diet alone had almost identical benefits for insulin sensitivity compared to gastric bypass surgery.
2. The metabolic benefits of diet and gastric bypass surgery were related to weight loss.
Evidence rating level: 2 (good)
Study Rundown: Previous studies have shown that bariatric surgery is far more effective than medical therapies for treating type 2 diabetes. However, many of these studies have results that are confused by the difference in weight loss between participants undergoing these procedures. For this reason, the effects of bypass surgery on major factors of type 2 diabetes pathogenesis such as beta cell function and insulin resistance, regardless of weight loss, are unclear. This study therefore evaluated whether gastric bypass surgery in subjects with obesity and type 2 diabetes offers metabolic benefits regardless of weight loss. The results of the study showed that both the diet and gastric bypass surgery brought metabolic benefits that were actually related to the resulting weight loss from the interventions. This prospective cohort study was limited by evaluating metabolic outcomes after weight loss between 16 and 24%. Therefore, the study results could not be extrapolated for weight loss above or below this range. netheless, assigning participants based on weight loss to control the confusing variables strengthened this study.
Click here to read the study in NEJM
Relevant Reading: Effects of Moderate and Subsequent Progressive Weight Loss on Metabolic Function and Adipose Tissue Biology in People with Obesity
In detail (prospective cohort): This prospective cohort study followed 33 participants in a single center in the United States. The participants in the study were diagnosed with type 2 diabetes and obesity. Participants who failed to achieve their target weight loss of 16 to 24% of the participant's original weight were excluded from this study. Participants underwent a comprehensive assessment of metabolic function before and after weight loss following Roux-en-Y bypass surgery in the stomach or low-calorie diet therapy. The diet group received weekly training on nutritional practices and packaged meals. Before the analysis, the participants were compared based on the percentage weight loss between the two intervention groups. Once participants achieved the target weight loss, body weight was maintained for three weeks before the final comprehensive assessment of metabolic function was performed. The primary result was the change in insulin sensitivity in the liver. The mean weight loss in the diet group was 17.8 ± 1.2% (range 16.1 to 20.4) and 18.7 ± 2.5% (range 16.0 to 24.4) in the surgical group. The insulin sensitivity in the liver increased after weight loss in the diet group (31.0 μmol / kg; 95% confidence interval (CI), 22.5 to 39.6) and in the operation group (25.1 μmol / kg; 95% CI , 16.4 to 33.8). There was no significant difference between the two groups (-6.5 μmol / kg; 95% CI, -15.7 to 2.7). In addition, beta cell function increased after weight loss in the diet group (1.83; 95% CI, 1.22 to 2.44) and in the operation group (1.11; 95% CI, 0.08 to 2, 15); However, there was no significant difference between the two groups (-0.71; 95% CI, -1.75 to 0.34). Interestingly, the weight loss in both groups resulted in a decrease in the concentrations of plasma bile acids, plasma branched chain amino acids and C5 acylcarnitine. However, the decrease in these plasma components was greater for the surgical group than for the diet group. Taken together, weight loss as a result of diet or gastric bypass surgery provided nearly identical benefits for insulin sensitivity in participants with type 2 diabetes and obesity.
© 2020 2 Minute Medicine, Inc. All rights reserved. work may be reproduced without the express written consent of 2 Minute Medicine, Inc. Inquire about licensing here. article should be construed as, and is not intended to be, medical advice by the authors or by 2 Minute Medicine, Inc.