β-Cell Function in Severely Obese Type 2 Diabetic Patients
Long-term effects of bariatric surgery
- Stefania Camastra, MD12,
- Melania Manco, MD3,
- Andrea Mari, PHD4,
- Aldo V. Greco, MD3,
- Silvia Frascerra, PHD12,
- Geltrude Mingrone, MD3 and
- Ele Ferrannini, MD12
- 1Department of Internal Medicine, University of Pisa School of Medicine, Pisa, Italy
- 2CNR Institute of Clinical Physiology, University of Pisa School of Medicine, Pisa, Italy
- 3Department of Medicine, Catholic University, Rome, Italy
- 4CNR Institute of Biomedical Engineering, Padua, Italy
- Address correspondence and reprint requests to Ele Ferrannini, MD, Department of Internal Medicine, Via Savi, 8, 56100 Pisa, Italy. E-mail: ferranni{at}ifc.cnr.it
Bariatric surgery in severely obese diabetic patients can restore glucose tolerance (1). Malabsorptive bariatric surgery (e.g., bilio-pancreatic diversion [BPD]) in nondiabetic subjects induces an improvement in insulin sensitivity that is greater than predicted by weight loss (2,3); such an effect can be demonstrated early after surgery (4). Impaired β-cell function is the main determinant of glucose intolerance, and modeling of C-peptide responses to graded glucose infusions (5) or oral glucose administration (6) makes it possible to estimate key dynamic parameters of β-cell function such as β-cell glucose sensitivity. The impact of bariatric surgery on β-cell function in diabetic subjects has been investigated using the intravenous glucose tolerance test (7). This test, however, can misjudge β-cell function as compared with more physiological challenges (such as the oral glucose tolerance test or mixed meals) because it explores only one specific aspect of islet function, namely the acute insulin discharge in response to a sudden maximal increment in plasma glucose concentrations (8). Recently, we have applied C-peptide–based modeling to reconstruct insulin secretion and β-cell function during a 24-h multiple-meal test (9). Here, we adopted this approach to analyze the long-term effects of BPD on glucose metabolism in morbidly obese patients with type 2 diabetes.
RESEARCH DESIGN AND METHODS—
We studied 10 morbidly obese (mean ± SE BMI 49.5 ± 2.9 kg/m2), non–insulin-treated type 2 diabetic patients (3 men and 7 women) (age 50 ± 2 years) whose weight had been stable (±2 kg) for the preceding 6 months. Oral antidiabetic drugs were discontinued 1 week before the baseline studies. The study protocol was approved by the local ethics committee, and all subjects provided informed written consent to participate.
Following the baseline studies, patients underwent BPD, consisting of a partial gastrectomy with a distal Roux-en-Y reconstruction (2), and were restudied 24 ± 2 months postsurgery. …
