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gastrointestinal hormone after bariatric surgery.pdf

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Figure 1. Roux-en-y
gastric bypass

Figure 2. Laparoscopic
adjustable gastric banding

Figure 3. Biliopancreatic

A surgical stapler is used to
create a small gastric pouch;
ingested food bypasses ~95%
of the stomach, the entire
duodenum, and a portion of
the jejunum.

The upper part of the stomach
is encircled with a constrictive
saline-filled tube; the amount
of restriction can be adjusted by
injecting or withdrawing saline

The stomach and small
intestine are surgically
reduced so that nutrients are
absorbed only in a 50-cm
“common limb.”

are characteristic of type 2 diabetes. Medical management
of diabetes involves a step-wise approach, from lifestyle
intervention (physical activity and nutrition therapy) to
oral antihyperglycemic agents and then insulin. It aims to
address the dual issues of defective insulin secretion and
insulin resistance, and often requires a combination of treatment modalities to achieve and maintain optimal glycemic
control. The recent understanding of the enteroinsular axis
and the role of glucagon-like peptide 1 (GLP-1) in maintaining glucose homeostasis paved the way for the use of GLP-1
analogues and dipeptidyl peptidase-4 inhibitors in clinical
practice. Although these agents have broadened the therapeutic options available for improving glycemic control,
remission of diabetes remains an elusive target.
Several gastrointestinal operations that were initially
designed to promote weight loss have been shown to induce
remission of type 2 diabetes and dramatically improve
other metabolic abnormalities, including hyperlipidemia
and hypertension (3). There is ample data to confirm the
safety and efficacy of conventional bariatric operations—
particularly Roux-en-Y gastric bypass (RYGB) (Figure 1) and
laparoscopic adjustable gastric banding (LAGB) (Figure 2)
—in morbidly obese patients (4,5).
The use of experimental procedures, as well as conventional bariatric operations, is increasingly being explored in
less obese patients who have diabetes, with generally favourable results; however, further assessment of the risk- benefit
ratio is needed. Several studies have demonstrated that the
amelioration of metabolic dysfunction is attributable not only
to weight loss and caloric restriction, but also to endocrine
changes resulting from surgical manipulation of the gut (6,7).

Figure 4. Sleeve
A longitudinal (sleeve)
resection of the stomach
reduces the functional
capacity of the stomach and
eliminates the ghrelin-rich
gastric fundus.

Several studies have demonstrated impressive improvements
in type 2 diabetes among patients with morbid obesity following a variety of gastrointestinal surgical procedures. In a metaanalysis of 136 studies involving 22 094 patients with type 2
diabetes resolution defined as persistent normoglycemia
without the need for diabetes medications, Buchwald and
colleagues (3) reported an overall 77% remission of type 2
diabetes after bariatric surgery. The mean procedure-specific
resolution of type 2 diabetes was impressive: 48% for LAGB;
68% for vertical banded gastroplasty (VBG); 84% for RYGB;
and 98% for biliopancreatic diversion (BPD) (Figure 3). It
must be noted, however, that most of these studies were retrospective, with a follow-up duration of only 1 to 3 years.
Two large case-series studies by Pories and colleagues
(330 patients) and Schauer and colleagues (191 patients)
focused principally on diabetes outcomes after RYGB (8,9).
Mean fasting blood glucose (FBG) decreased to near-normal
levels (6.5 and 5.4 mmol/L in the 2 studies, respectively), and
glycated hemoglobin fell to normal levels (6.6% and 5.6%,
respectively) without diabetes medication in 89% and 82%
of patients, respectively. The multicentre Swedish Obese
Subjects (SOS) study (10) compared bariatric surgery (LAGB,
n=156; VBG, n=451; RYGB, n=34) vs. a control group of
well-matched obese patients managed conservatively. Mean
fasting glycemia tended to increase during the study in nonsurgical controls (18.7% at 10 years), whereas a substantial
decrease was seen in surgical patients at 2 years (−13.6%) and
10 years (−2.5%). At 2 years, 72% of subjects with type 2
diabetes in the surgical group achieved disease remission,