β-cell function determines bariatric surgery outcome
MedWire News: Diabetes remission after bariatric surgery seems to be dependent on the degree of β-cell dysfunction present before patients undergo the procedure, suggest researchers.
Improvement in β-cell glucose sensitivity after Roux-en-Y gastric bypass (RYGB) represents the main determinant in the remission of Type 2 diabetes, but this depends on the starting degree of β-cell dysfunction, they say.
As reported in Journal of Clinical Endocrinology and Metabolism, Monica Nannipieri (University of Pisa, Italy) and colleagues assessed the effects of improved insulin sensitivity and β-cell function on diabetes remission by studying 32 Type 2 diabetic and 11 normal glucose tolerance (NGT) patients with morbid obesity who underwent Roux-en-Y gastric bypass.
The team recorded the patients' lipid, plasma glucose, insulin, C-peptide, and HbA1c concentrations 1 month prior to the surgery and again at 45 days and 12 months after the procedure. They also noted the patients' height, weight, BMI and blood pressure measurements.
The researchers report that after 45 days, diabetes had remitted in 9 patients and by the end of the 1-year follow-up, remission was seen in a further 16 patients.
They also found that insulin sensitivity improved after surgery in both groups and closely tracked with BMI changes.
However, among Type 2 diabetic patients, although β-cell glucose sensitivity did increase early after surgery it still remained well below that of the nondiabetic patients (median, 48 pmol/min.m2.mM vs median, 100 pmol/min.m2.mM).
Further analysis revealed that baseline β-cell glucose sensitivity was significantly worse among diabetic patients than among the NGT group, whereas baseline fasting and total insulin secretion were similar between the two groups.
Furthermore, baseline β-cell glucose sensitivity was progressively worse in early remitters, late remitters, and nonremitters, at medians of 54, 22 and 4 pmol/min.m2.mM, respectively, and proved the only predictor of failed remission in logistic regression analysis.
"The current results document that, although baseline insulin sensitivity is similarly depressed in remitters and nonremitters, β-cell glucose sensitivity and rate sensitivity are progressively worse at baseline, and fail to improve, in nonremitters as compared with remitters, thereby emerging as a strong predictor of remission," write Nannipieri and colleagues.
They add: "Our data suggest that on a background of better β-cell function, the improvement in β-cell glucose sensitivity after RYGB represents the major determinant in the remission of Type 2 diabetes."
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By Sally Robertson