Gastric bypass surgery reveals independency of obesity and diabetes melitus type 2

Abstract

Background: Roux-en-Y gastric bypass surgery is widely applied to ameliorate morbid obesity, including diabetes in people with type 2 diabetes. The latter vanish a few days after surgery for many, but not in all patients before any weight reduction has occurred. The explanation for this change in metabolic status is poorly understood, but the observation may suggest that the fate obesity and diabetes is only partly linked after surgery.

Methods: The trajectories of weight reduction measured as reduced body mass index (BMI) in 741obese subjects with and without diabetes were evaluated. Evaluation was performed on three groups: 1) subjects that were non-diabetic before and after surgery; 2) subjects that were diabetics before surgery but non-diabetics after surgery; and 3) subjects that were diabetics before surgery and remained diabetics after surgery. The diabetic state was established at HbA1c above 48 mmol/mol.

Results: The trajectories differ significantly between groups and any sub-populations of groups, the latter identified by the distance between individual trajectories using a k-means procedure. The results suggest that different domains in the enormous genetic network governing basic metabolism are perturbed in obesity and diabetes, and in fact some of the patients are affected by two distinct diseases: obesity and diabetes mellitus type 2.

Conclusion: Although RYGB "normalized" many glycaemic parameters in some of the diabetic subjects apparently converting to a non-diabetics state, other diabetic subjects stay diabetic in the context of the new gut anatomy after surgery. Thus, the obesity part of the glycaemic derangement may have been ameliorated, but some defects of the diabetic state had not.

Fig. 1

Trajectories of the five clusters (out of 8) containing five or more subjects. The data was pooled for all the subjects in the clusters increasing the number data points to no less than 40, i.e. 148 subjects and not less than 750 measurements were included in the analysis. Here the trajectories for the non-diabetic sub-populations are shown. The red dot indicates the point of normalization of BMI at time zero i.e. the penultimate data points before surgery. Although the trajectories seem alike most of them differed significantly. See Additional file 6: Table S6 for statistical data for the clusters for all sub-populations (including the diabetic sub-populations)