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The Role of Gastrointestinal Metabolic Surgery in the Management of Type 2 Diabetes
An informative example comes from treatment of coronary artery different BMI categories.
52
Also, while BMI alone is a good predictor of
disease. A population-based study demonstrated that the seven-year the risk of developing diabetes and/or metabolic syndrome, it is less
incidence rates of MI in subjects with diabetes without prior MI at adequate as a measure of the overall risk of morbidity and mortality
baseline (20.2%) were essentially the same as the incidence rates of in patients with established diabetes.
MI in subjects without diabetes but with prior MI (18.8%). The hazard
ratio for CHD deaths between these two groups was not significantly There is therefore no evidence that a specific BMI cut-off could predict
different from 1.0.
33
Guidelines from the American College of diabetes-specific risks, and recent investigations of metabolic surgery in
Cardiology (ACC)/American Heart Association (AHA) agree that less obese patients
53–56
show that no specific level of BMI can provide a
coronary artery bypass graft (CABG) surgery should be performed in distinction between patients who would benefit from surgery and those
patients with stable angina in certain settings.
34
In 2000, the US who would not with regard to resolution/improvement of diabetes.
57
national average mortality rate for CABG was 3.5%.
32
Bariatric surgical Using current BMI cut-offs may also delay a potentially life-saving option
procedures, by comparison, demonstrate a mortality rate that is for patients with lower BMI but at similar risk from diabetes.
merely one-tenth as high as that for CABG
35
and offer long-term Furthermore, BMI-based policies might be perceived as discriminatory
resolution of diabetes, yet are rarely considered in the algorithm of since the BMI-related risk is influenced by gender and ethnic
diabetes management. differences. For example, an individual of South Asian descent with a
large waist circumference, several comorbidities (including diabetes),
A Return on Investment and a BMI of 34kg/m² would have a substantially different risk–benefit
Cremieux and co-workers
8
have recently compared bariatric surgery profile for surgical treatment of diabetes than an individual of European
patients with obese control patients who did not have surgery. The descent with a normal waist circumference, one comorbidity, and a BMI
improvements in morbidity and mortality contributed to decreases in of 36kg/m². However, based on our current guidelines, the latter would
healthcare utilization.
18,37,38
All costs for bariatric surgery are recouped be offered surgery while the former would not. The growing evidence
within two years for laparoscopic patients and within four years for indicating that the antidiabetic mechanisms of some gastrointestinal
open surgeries.
8
operations cannot be explained by changes in food intake and
bodyweight alone
58,59
suggests that it might be appropriate to expand the
This return on investment should not be a surprise considering the well- indications for surgical treatment of diabetes to patients who do not
documented immediate and long-lasting reductions on myriad obesity- meet existing BMI-based criteria.
related comorbid conditions.
6,7,16,32,35,39–47
Several small studies and case reports have examined the efficacy of
Surgical Treatment of Type 2 Diabetes— surgical treatment of type 2 diabetes in overweight and mildly obese
Patient Selection patients. Cohen et al. performed RYGB in 37 type 2 diabetes patients
Current National Institutes of Health (NIH) guidelines define eligibility for with BMIs between 32 and 35kg/m². Diabetes resolved in all patients
surgical management of morbid obesity using criteria primarily based on post-operatively, with HbA
1c
levels of <6% off any oral antidiabetic
body mass index (BMI). Specifically, patients with a BMI >40kg/m² or agents.
53
Lee and co-workers reported excellent long-term control of
with a BMI >35kg/m² with comorbidities (including diabetes) are eligible diabetes in patients with BMIs between 27 and 35 who underwent
for bariatric surgery.
48
BMI has been adopted worldwide as the RYGB.
54
Cohen’s group also reported post-operative resolution of
predominant measure to guide classification of obesity and to diabetes (with HbA
1c
levels <6% off all antidiabetic medications) in two
determine risk of morbidity and mortality due to obesity.
49
Due to these patients with BMI between 29 and 31kg/m² who had undergone
criteria and classifications, BMI is frequently thought of as a primary laparoscopic duodenal–jejunal bypass (DJB).
42
Chiellini et al.
23
studied
measure of risk associated with obesity and is one of the most patients with type 2 diabetes and BMI 26–33kg/m² who underwent
important reasons why a surgical operation is warranted. biliopancreatic diversion. Post-surgery, all patients had normalized
blood glucose and dramatic improvement in all measures of glucose
While BMI does represent one conveniently calculated parameter of homeostasis. A recent study looked at the effect of laparoscopic DJB on
obesity, it is far from a fully inclusive measure of all risk. For instance, 20 type 2 diabetes patients with BMI between 20 and 30kg/m². There
ethnicity plays a large role in obesity risk. One meta-analysis found was a significant reduction in fasting glycemia and HbA
1c
over six
that the relationship between percent body fat and BMI differed months post-operatively, and a significant increase in C-peptide
among ethnic groups such that, for a given level of body fat, age, and between the third and sixth months post-operatively.
55
DePaula et al.
gender, different ethnic groups have different BMI levels.
50
Razak et al. have also reported dramatic improvement of diabetes in non-obese
demonstrated that South Asians and Chinese have distributions of patients undergoing laparoscopic ileal interposition.
56
elevated glucose and lipid factors similar to Europeans at significantly
lower BMI values.
51
This supports that BMI-centric definitions of Future Research
obesity and associated risk are applicable primarily to Caucasians. Sample sizes and duration of post-operative follow-up are insufficient
Waist circumference should also be considered in an obesity risk to assess long-term efficacy and the safety of surgery in non-obese
profile. NHANES reported that patients who had a high waist patients. Large-scale randomized clinical trials with optimal medical
circumference were significantly more likely to have hypertension, and lifestyle therapy of diabetes as the comparator will be critical to
diabetes, dyslipidemia, and the metabolic syndrome compared with advance the field, to define the role of surgery, and to implement
those having a normal waist circumferences. This was the case across surgery as a mainstay for type 2 diabetes therapy. These trials may
US ENDOCRINOLOGY 55
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