Weight loss from bariatric surgery can improve not only insulin resistance but also adipose tissue function. Using the metabolic profiles of patients, for the first time, researchers were able to show the correlation between changes in levels of growth hormone and insulin-like growth factor 1 (IGF-1) and improvements in adipose tissue function, although not insulin sensitivity.
In the International Journal of Obesity, researchers from the German Diabetes Center, a DZD partner, published an analysis of 79 obese patients participating in the BARIA-DDZ study. The initial body mass index (BMI) of the patients was 50.8 ± 6.3 kg/m2. They underwent treatment using either sleeve gastrectomy (n=30) or gastric bypass (n=49). Postoperative examinations were carried out at weeks 2, 12, 24, and 52 after surgery. A control group consisting of 24 healthy and lean probands (BMI 24.3 ± 3.1 kg/m2) provided comparative data.
Higher Glycemia and Leptinemia Levels at the Start of the Study
At the start of the study, those who were obese displayed higher blood glucose and leptin levels compared with those of normal weight. Their muscle, adipose tissue, and liver insulin resistance levels were more pronounced than those observed in the control group. Their growth hormone (GH) and IGF binding protein (IGFBP1) levels were lower. In contrast, the IGF-1 levels in both groups were comparable.
At 52 weeks after surgery, patients in the obese groups had lost 33 per cent of their body weight and doubled their muscle insulin sensitivity. This was coupled with a continuous increase in GH, IGF-1 and IGFBP1 and a reduction in leptin levels.
- The GH increase correlated with a reduction in the levels of free fatty acids, adipose tissue insulin resistance, and blood insulin levels, but not with a change in body weight, peripheral insulin sensitivity, or glycemia or leptinemia levels.
- In contrast, the IGF-1 increase correlated with a reduction in the levels of c-reactive protein, a key inflammatory marker.
Summarizing the results, lead author Sofiya Gancheva said that “the changes in GH and IGF-1 following surgically induced weight loss are likely not related to improved leptin secretion or insulin sensitivity, but rather to the restoration of adipose tissue function and improvement of subclinical inflammation”.
Sofiya Gancheva, Sabine Kahl, Christian Herder, Klaus Straßburger, Theresia Sarabhai, Kalliopi Pafili, Julia Szendroedi, Matthias Schlensak & Michael Roden. Metabolic surgery-induced changes of the growth hormone system relate to improved adipose tissue function. International Journal of Obesity 23 Mar 2023, https://doi.org/10.1038/s41366-023-01292-7