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 = underweight20-25 = normal25-30 = overweight30-40 = 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

0

5

10

15

20

25

30

35

USA MEXICO UK SLOVAKIA GREECE AUSTRALIA NZ HUNGARY SPAIN IRELAND TURKEY SWEDEN FRANCE J APAN

Worldwide Obesity Prevalence (%)

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

0

10

20

30

40

50

60

70

80

90

DM Lipids HT SleepApnoea

% amelioration

Resolution / improvement of comorbidities

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 SurgeryBMI > 40 or BMI >35 with ComorbidityNICE: CG43

Exhausted non surg methodsFit for opWillingFirst line for BMI>50 Part of MDTIn 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