Explained: How Non-invasive Weight Loss Surgery Helps Control Diabetes

Bariatric surgery is an operation conducted to aid significant weight loss in patients. It involves making major alterations to the stomach and intestine. Sleeve gastrectomy is one of the four types of bariatric surgeries which focuses on limiting the amount of food one can eat by removing 70%-80% of the stomach.

Researchers at AIIMS claim that bariatric surgery is more effective than either standard or intensive medical treatment in patients with severe obesity and type 2 diabetes, with around 70-80% patients achieving significant improvement.

Who Is the Surgery For?

FactChecker spoke to Dr Sandeep Aggarwal, lead author of the study and one of the unit heads of the Department of Surgical Disciplines at AIIMS, Delhi, and Dr Ramen Goel, gastroenterologist and bariatric surgery specialist and founder of Centre for Metabolic Surgery, Mumbai.

This is a follow-up study of 20 patients with class 1 obesity (low-risk) and type 2 diabetes who underwent the sleeve gastrectomy surgery between March 2012 and March 2015.

The surgeons said this surgery is usually performed on people who have tried various weight regimes and haven't had long lasting results. It's offered to those who have uncontrolled diabetes and are overweight by 10-12 kgs (27.5 BMI), those who are only overweight and do not have any underlying diseases and those who have high blood pressure and a BMI of 30. Body mass index is measured by dividing weight in kilogrammes by height in meters squared.

According to Dr Aggarwal, besides weight loss, about 80% of patients have complete remission of diabetes after the surgery. This means they are off medications and treatment for a long period of time. "In our study, we focussed on a small group of patients and considered diabetes as the primary end point. We didn't primarily operate these patients for weight loss but looked at improvement in diabetes in mild obese patients over a five-year period," Dr Aggarwal told FactChecker.

"The volume of the stomach is roughly between 1.2 to 1.5 litres. Think of it as a bag. We remove a curtain of fat which is attached to one of the edges of the stomach. Essentially, we convert a bag by stapling it into a tube which is roughly 100-120 cubic centimetres and has a diameter of 1.4 cms initially," explained Aggarwal. Since the stomach is smaller, the capacity of the stomach reduces and a major part of the appetite-stimulating hormone (ghrelin) lessens.

Likewise, Dr Ramen Goel of CMS said it's a less invasive procedure. "It's done only on the stomach and intestines are not touched, while in bypass we do it on both these organs. About 70% is removed or dissected and hence it's a much smaller stomach," said Dr Goel.

How Surgery Controls Diabetes?

Type 2 diabetes is a complex metabolic disease caused by insulin resistance and progressive failure of pancreatic beta cells, resulting in hyperglycemia (high blood glucose or too much sugar in blood due to lack of insulin).

Insulin, a hormone which is made by the pancreas, enables glucose to enter the cells. If a person's body does not make enough insulin, the glucose cannot get into the cells and hence stays in the blood. To add to this, obesity acts as a risk factor for type 2 diabetes because it contributes to its development by inducing insulin resistance and inflammation which in turn hinders glucose regulation.

Both doctors said the surgery targets hormones in the digestive tract. "It leads to a change in the hormones which are produced in the intestines. These hormones are considered very important for blood sugar control. They affect pancreas and insulin secretion and change the healthy bacteria in the intestine. When we do conduct this surgery, the unhealthy bacteria reduces and the healthy ones overgrow," explained Dr Goel.

Although sleeve gastrectomy does not change the intestinal anatomy, it has been found to cause significant improvement in the glycemic index (rating system for foods containing carbohydrates and shows how quickly each food affects one's blood sugar level when that food is eaten on its own) in the short term, according to the AIIMS study. "In the immediate postoperative period, even before any significant weight loss, improvement in plasma glucose levels occurs because of increased insulin sensitivity and improved beta cell functioning, leading to marked improvement in the early phase of insulin release, which is usually defective in patients with type 2 diabetes," read the study.

Blood sugar level spikes each time one eats and since, after the surgery, the person eats less, it leads to blood sugar control, the bariatric surgery specialist added.

Dr Aggarwal also explained that several studies have reported short and medium-term outcomes of sleeve gastrectomy but that the literature beyond three years is scarce. "In our study, 16 out of 17 patients were remitted or showed improvement in the disease. A simpler procedure like sleeve gastrectomy is more feasible than a complex gastric bypass procedure," said Dr Aggarwal, who co-authored the study, which was published in October 2021 in Obesity Surgery, a medical journal.

The estimated number of diabetes patients between the age of 20-79 years in India increased by 11.5% in four years — 77 million in 2019 from 69 million in 2015, said Minister of State for Health and Family Welfare Ashwini Kumar Choubey in a written response in the Lok Sabha on February 12, 2021, which sourced data from International Diabetes Federation (IDF). As of 2019, there were 1.71 lakh juvenile diabetes patients (0-19 years) in the country and around 463 million adults were living with diabetes till 2019. Moreover, it is predicted that by 2045, it will rise to 700 million, according to the IDF Diabetes Atlas Ninth Edition 2019.

Additionally, COVID-19 too has had a major influence on the increased demand of bariatric surgery, say the surgeons. Both doctors said consultations and surgeries are increasing by 20%-30% currently. This was, however, not the case during the lockdown. "The numbers are increasing and are not symbolic of the real numbers. We see about 50-70 patients a month although all don't opt for the surgery," said Dr Goel.

Similarly, Dr Aggarwal also said, "Initially the numbers were less, but in the last 3-4 years, AIIMS tested about 120 to 140 patients between ages 30 and 50 a year."

"People have become more conscious. In fact, those who are overweight had more serious COVID-19 complications and there were more deaths among them. Plus, lockdowns have caused gyms to close and that resulted in people gaining weight. So, the demand has increased," Dr Goel concluded.