Metabolic Effects of Bariatric
Surgery on Diabetes
Mr Paras Jethwa BSc MD FRCS FRCS(Gen Surg)
Consultant Laparoscopic Surgeon
Definitions
• Body Mass Index = weight/height2
< 20 = underweight
20-25 = normal
25-30 = overweight
30-40 = obese
> 40 = morbidly obese
• Excess Weight = Current Weight – Ideal Weight
BMI > 30
1991
BMI > 30
1992
BMI > 30
1993
BMI > 30
1994
BMI > 30
1995
BMI > 30
1996
BMI > 30
1997
BMI > 30
1998
BMI > 30
1999
BMI > 30
2000
BMI > 30
2001
Worldwide Obesity Prevalence (%)
35
30
25
20
15
10
5
0
US A
M EXI C O
UK
S L OVA K I A
GR EEC E
A U S TR A LI A
NZ
H U N GA R Y
S P AIN
I R EL A N D
T U R K EY
S WED EN
FR A N C E
JAP AN
Obesity Related Mortality
Type 2 DM
• >80% have BMI >25
• 50% obese, 10%>40%
• Modest weight loss helps control
• BUT - 95% will fail with diet
• Proposed in mid 90’s that T2DM
– “Surgical disease”
– Foregut hormone stimulation
Surgical Options
• Restrictive vs. malabsorption
• Restrictive:
– Generating saiety signals
• Malabsorpative:
– Gastric restriction
– Duodenal and upper jejunal bypass
• Extreme (BPD & Switch)
– Only last 50cm of SB used for digestion
Laparoscopic Gastric Band
• Mean = 47% EWL
• Best for
– BMI < 47 kg/m2
– Regular meal patterns
– Non sweet eaters
• Mortality risk 1:800
• Morbidity risk 1:100
• 15% bands need revision
Laparoscopic Gastric Bypass
• Mean = 72% EWL
• Best for
– All BMI
– Sweet eaters and grazers
– Diabetics
• Mortality risk 1:300
• Morbidity risk 1:75
Laparoscopic Sleeve
•
•
•
•
•
•
•
Mean = 75% EWL?
Easy maintence
One long suture line
Poorer longterm
Removes Ghrelin producing cells
Mortality risk 1:400
Morbidity risk 1:100
Laparoscopic Mini Gastric Bypass
• Mean = 80% EWL
• Best for
– All BMI
– Grazers
– T2DM
• Mortality risk 1:500
• Morbidity risk 1:80
• Lower long term risk of metabolic
complications
• Extensively practiced in US
MGB success
What mechanisms are at work?
Bypass factors
• Foregut vs. Hindgut theories
– Gherlin
– Glucagon like peptide
– Gut derived glucadonotropic signalling
• Diabetic effect seen before weight loss
– Clear division contributes
– RYB vs. Banding for speed of control
Weight loss factors
• Improvements insulin action/reduced
resistance
• Relieve secretory pressure on ß cells
• Early effect:
– Calorific reduction - increase insulin sensitivity
• Later effect:
– Absolute weight loss  glycaemic control
Are the effects longlasting?
• Maximum wt loss is at 1-2 years
• 30-50% excess wt loss at 6/12
• 10-14 years post op - more favourable levels
of :
– Cholesterol
– DM
– HT
Benefits
•
•
•
•
621 studies with 135, 246 patients
Mean age - 40.2 years
Mean BMI - 47.9
80% Female
•
•
•
•
56% EBWL
78% resolution of diabetes
BPD>RYB>LAGB
Effect static at 2 years
• Case controlled prospective
study
• Surgery v control
• 4047 patients
• 99.9% follow up
• Average 10.9 year follow up
• Prospective SOS trial:
– Glucose/lipids/BP
• 10.9 year FU - 30%
mortality
Non T2DM effects
• SOS study
• 50% reduction in IHD
• 85% reduction in sleep apnoea
• Life expectancy improves up to 89%
• Up to 40% reduction in premature death
• 60% reduction in cancer deaths
• Fatal IHD halved
Resolution / improvement of
comorbidities
90
80
70
60
50
40
% amelioration
30
20
10
0
DM
Lipids
HT
Sleep
Apnoea
Prognostic factors for DM
remission
• Type of op
• Pro:
– Early rapid weight loss
– Preoperative insulin dose
• Against:
–
–
–
–
Diabetes dutation (B cell mass)
High HbA1c
Insulin vs. oral therapy
Diabetic complications (retinopathy etc.)
• Unsure:
– FH
– Late onset type 1
Risks
• Remarkably safe
• Mortality 0.1% to BPD 1.1%
• 5-10% acute comps
– Bleeds
– Int. hernia
– Anastomotic issues
– Nutrition
– Emotional
• Hypoglycaemia if medication unaltered
Metabolic Surgery
BMI > 40 or BMI >35 with Comorbidity
NICE: CG43
Exhausted non surg methods
Fit for op
Willing
First line for BMI>50
 Part of MDT
In young in exceptional circumstances
 psychological factors etc.
Diabetes
• Bypass:
– Type 2 - 87% resolution
• Band
– Type 2 - 73% resolution
• 92% mortality risk reduction
• Clinically and cost effective for moderate to
severe obesity
Role of banding?
• RCT of 80 patients
• 2 year follow up
• 87% v 22% excess weight
loss
• Significant reduction in
metabolic syndrome
• 50-77% of obese
adolescents carry their
obesity into adulthood
Adolescents
• Rapidly growing group in US
– Sequential family members
• Extremely obese teen
– Treatment of choice?
• Radical step BUT…….
– T2DM not uncommon in teens now
– Given that we are following US trends…
Summary
•
•
•
•
Obesity plays a key role in pathophysiology
Roux en Y bypass most effective
Effects not just related weight related
Useful adjunct in obesity esp. when DM difficult
to control
• Surgical diversion leads to release of incretin
• Type 2 DM evaluated at MDT