BY PROF DATUK DR NIK RITZA KOSAI NIK MAHMOOD

DR HARDIP SINGH GENDEH and

DR MARDIANA MARDAN

Diabetes is classified as Type I , Type II and Gestational Diabetes Mellitus ( GDM ). When sugar levels build up in the blood and urine , one may experience symptoms such as frequent urination , increased thirst and appetite .

Obesity and diabetes

At present , diabetes management focuses on maintaining normal blood sugar levels and avoiding too low levels ( hypoglycemia ). This is achieved by a healthy lifestyle , dietary changes and medications ( oral antihyperglycemic agents and insulin ).

Diabetic patients are encouraged to lose weight as there is a clear link between weight and diabetes . Weight loss can prevent progression from prediabetes to diabetes , decrease the risk of cardiovascular disease or result in a partial remission of diabetes .

Studies showed that increase in the prevalence of Type 2 diabetes has contributed significantly to the parallel increase in overweight and obesity . The general prevalence of abdominal obesity and diabetes in Type 2 diabetes is inseparable ; in particular , the majority of Malaysians with Type 2 diabetes are obese-related . Waist circumference is a risk factor highlighted by the Malaysian Clinical Practice Guidelines of diabetes .

Weight loss and diabetes

Easier said than done ! Many diabetics are trying to cut down their weight but to no avail . Bariatric surgery comes to the rescue !

Historically , bariatric surgery was thought to promote weight loss by causing gastric restriction and / or decrease in food absorption . Recently , it was discovered that parts of gut differentially influence glucose control . The advantage of bariatric surgery in patients who also develop Type 2 diabetes has resulted in a shift in the emphasis on weight loss towards enhancing glycemia and other metabolic elements , hence , the term “ metabolic surgery ”.

There are various types of metabolic surgery , including laparoscopic adjustable gastric bands , vertical sleeve gastrectomy ( VSG ), Roux-en-Y gastric bypass ( RYGB ) and biliopancreatic diversion ( BPD ). Commonly performed procedures worldwide are the VSG and RYGB .

Diabetes remission rates vary based on the form of procedure , and disease duration . It has repeatedly been shown that most patients retain strong postoperative glycemic regulation despite decreased or no glucose-lowering medication .

Vertical Sleeve Gastrectomy which reduced the volume of the stomach .

How does bariatric / metabolic surgery result in a successful weight loss and remission of diabetes ? Unfortunately , the exact mechanisms are still being studied . Bariatric / metabolic surgery causes three phases of anatomical changes : ( i ) gastric restriction ; ( ii ) removal of duodenum and upper intestine ; ( iii ) quick transfer of food to intestines or small typical channels .

These anatomical improvements cause physiological and molecular changes that aid in the resolution of Type 2 diabetes . These modifications , acting via peripheral and central pathways , would result in decreased liver ( hepatic ) glucose , increased absorption of tissue glucose , enhanced insulin sensitivity and improved beta-cell activity .

Beta cell and insulin production

Beta cells in the pancreas are responsible for the secretion of insulin . Beta-cell responses resemble two peaks also known as a biphasic pattern . An acute initial peak , representing the first phase insulin secretion happens within the first half hour after a meal .

This is accompanied by a steady rise in insulin secretion , resulting in a smaller volume hump 30 – 180 minutes after meals . Although the concentration of blood glucose is the major stimulus of fasting insulin secretion , there is an important after meal ( postprandial ) role for gastrointestinal tract-derived signals , mainly gut hormones released .

This is known as an incretin effect , which makes for an increased secretion of insulin when a glucose load is from the

Roux en Y Gastric Bypass which bypasses the stomach to the jejunum .

oral route , which may lead to as much as half the insulin secretion following a meal . Two incretin gut hormones , glucagon-like peptide 1 ( GLP-1 ) and glucose-dependent insulinotropic polypeptide , are the primary drivers of intestinal nutrient-induced insulin secretion ( GIP ).

In the case of Type 2 diabetes , it is the result of the gradual failure of pancreatic beta-cell function with increasing insulin resistance . Once the pancreas is unable to compensate for insulin resistance , an increase in blood glucose levels ( hyperglycemia ) develops , leading to the acceleration of beta-cell deterioration characterised by the loss of sensitivity and an impaired insulin secretion .

Metabolic surgery partly restores the dysfunction of the ß-cell . The enhanced GLP-1 secretion is assumed to be a significant weight loss independent factor that leads to the postoperative change after metabolic surgery .

Insulin sensitivity

After a meal , insulin release firstly suppresses liver glucose production and allowing glucose uptake into our tissues .

In insulin resistance , higher levels of insulin required to compensate for hyperglycemia . Following metabolic surgery , there is a marked improvement in insulin sensitivity that differs depending on the timing : early versus late postoperative period .

This early progress is secondary to a rise in liver insulin sensitivity as demonstrated by a decline in the body ’ s glucose production . Peripheral insulin sensitivity , including skeletal muscle and fat tissue , does not alter during the early postoperative cycle , but increases steadily afterwards and has a near association with weight loss . In the late postoperative cycle ( three to six months after surgery ), weight loss plays an important in additional insulin sensitivity .

Glucose absorption

After metabolic surgery , there are changes in the glucose metabolism within the gut . A lower glucose absorption has been shown to happen in RYGB and VSG , although , the mechanisms are different .

After RYGB , undigested nutrients