Alberto Benetti, MD, from Universita degli Studi di Milano, and colleagues assessed glucose metabolism (blood glucose and serum insulin levels and homeostasis model assessment of insulin resistance [HOMA-IR] index) and cholesterol metabolism (absorption: serum campesterol and sitosterol levels; synthesis: serum lathosterol levels; catabolism: rate of appearance and serum concentrations of serum 7-α- and serum 27-OH-cholesterol after infusions of deuterated 7-α- and 27-OH-cholesterol in sequence) in grade 3 obesity subjects undergoing bariatric bypass surgery and gastric banding. Measurements were taken before and six months after surgery.
The researchers found that baseline values were similar in all subjects. In both groups, weight loss and blood glucose, insulin levels, HOMA-IR, and triglycerides decreased similarly. Serum cholesterol, low-density lipoprotein cholesterol, non-high-density lipoprotein cholesterol, serumsitosterol, and campesterol levels decreased and lathosterol levels increased only in bypass subjects. Serum 27-OH-cholesterol decreased in both groups, but only in the bypass group was there a significant increase in 7-α-OH-cholesterol.
"Malabsorptive surgery specifically affects cholesterol levels, independent of weight loss and independent of glucose metabolism and insulin resistance," the authors write.