Alterations in proinsulin and insulin dynamics, HDL Cholesterol and ALT after gastric bypass surgery. A 42-months follow-up study.

BACKGROUND: Roux-en-Y gastric bypass (RYGBP) powerfully reduces type 2 diabetes (T2DM) incidence. Proinsulin predicts development of T2DM. Adjustable gastric banding is associated with lowered proinsulin but after RYGBP information is scant.
METHODS: Twenty-one non-diabetic morbidly obese patients who underwent RYGBP surgery were evaluated before (baseline), at 12 months (first follow-up), and at 42 months, range 36-50 (second follow-up), after surgery and compared to a control group, matched at baseline regarding fasting glucose, insulin, proinsulin, alanine aminotransferase (ALT), high-density lipoprotein (HDL) cholesterol, and body mass index (BMI).
RESULTS: In the RYGBP group, fasting serum proinsulin concentrations were markedly lowered from 13.5 to 3.5 pmol/l at first follow-up and to 4.9 pmol/l at second follow-up (p < 0.001, respectively). Fasting insulin concentrations were reduced from 83.4 to 24.6 pmol/l at first follow-up (p < 0.001) and to 36.4 pmol/l at second follow-up (p < 0.01). ALT was lowered from 0.62 to 0.34 mukatal/l at first follow-up and continued to lower to 0.24 mukatal/l at second follow-up (p < 0.001, respectively). The further decrease between first and second follow-up was also significant (p = 0.002). HDL cholesterol increased from 1.16 to 1.45 mmol/l at the first follow-up and continued to increase at second follow-up to 1.58 mmol/l (p < 0.001, respectively). The further increase between first and second follow-up was also significant (p = 0.006). The differences between groups at first follow-up were significant for BMI, proinsulin, insulin, ALT, and HDL cholesterol (p = 0.04-0.001).
CONCLUSION: RYGBP surgery in morbidly obese patients is not only characterized by markedly and sustained lowered BMI but also lowered concentrations of proinsulin, insulin, and ALT and increased HDL cholesterol.