Insulin Resistance

The Connection of Insulin Resistance, Diabetes & Bariatric Surgery

November 16, 2020

Insulin Resistance, Diabetes & Bariatric Surgery

The scourge of diabetes affects the entire population of the world. In fact, someone in the world dies from complications associated with diabetes every 10 seconds. Across all populations, 90% of type 2 diabetes mellitus (T2DM) with insulin resistance diagnoses are attributable to excessive body fat. The connection between insulin resistance and diabetes is contributing to the decreased health of many people.

In the United States, if the current disease trends continue, it is predicted that 50% of adults will have prediabetes or T2DM by the end of this decade.

Type 2 Diabetes & Insulin Resistance

Type 2 diabetes mellitus is a complex disease. It is characterized by insulin resistance and results in high blood sugar. Elevated blood sugar affects the entire body. Obesity is a risk factor for developing T2DM because it also causes insulin resistance. 

These two diseases are linked to such a degree that women at 18, who have a body mass index (BMI) of 30 to 35 have a 54.6% lifetime risk of developing diabetes. This risk is increased to 74.4% if the women have a BMI of over 35 at age 18. 

The American Diabetes Association goal for hemoglobin A1C is less than 7% in patients with T2DM. A reduction in body weight will assist patients with achieving better blood sugar control.

Along with medications, better dietary habits and exercise are often the first line of treatment for patients with T2DM. Reduction of excess body weight by 5 to 10% can lead to a decreased risk of disease progression and improved blood sugar control.

Diet and exercise can result in weight loss; however, the loss is not maintained in 90 to 95% of patients. This has led to bariatric surgery becoming a treatment option for patients with diabetes and obesity.

Benefits of Bariatric Surgery, Insulin Resistance & Type 2 Diabetes

Bariatric surgery comes in two general forms, restrictive procedures, and combination procedures. The combination procedures combine volume restriction with an intestinal rearrangement which causes the gastrointestinal system to absorb less of what is consumed. The outcomes show that bariatric surgery impacts Type 2 Diabetes.

All of these procedures are designed to allow patients to lose weight, generally over 60% of excess body weight. In the United States, there are three popular bariatric surgeries being done. They are the Sleeve Gastrectomy, the Roux-en-Y gastric bypass, and the Duodenal Switch. These operations are not equal in how much they can affect T2DM. 

The Sleeve Gastrectomy

The sleeve gastrectomy is a restrictive operation. The operation is done by making the stomach smaller as a portion of it is removed from the body. The operation is purely restrictive and does not have any work done to the intestines.

This operation is the most popular weight loss surgery done around the world, but it has the lowest percentage of diabetes resolution. Studies have shown that five years after surgery 23% of patients have resolution of their diabetes. 

The Gastric Bypass

The gastric bypass operation is considered the ‘gold-standard’ bariatric surgery.  It is the operation that has been around the longest time. All newer operations are compared to the Roux-en-Y gastric bypass. 

This operation is a combination procedure because it reduces the size of the stomach to about 30 milliliters. It also results in a rearrangement of the intestines where most of the stomach and between 100 to 150 cm of the small intestine is bypassed resulting in malabsorption. The Roux-en-Y gastric bypass operation has been shown to have long-term diabetes resolution in 29 to 83% of patients.

The Duodenal Switch

The duodenal switch operation is another combination procedure. It involves first removing a portion of the stomach like the sleeve gastrectomy procedure. Then the surgeon rearranges the intestines to bypass a longer segment than in the gastric bypass procedure. It results in the patient having about 300 cm of functioning intestine. This adds a significant amount of malabsorption. With the increased malabsorption patients are having better resolution of T2DM. It has been shown that up to 98% of patients had resolution of T2DM 10 years after surgery.

Although the data shows that there are different rates of diabetes cure based on the procedure performed, the one constant finding has been that the earlier surgery is performed the higher likelihood of complete diabetes resolution after bariatric surgery.

There are different theories of exactly how the operation itself induces the change in metabolism to cause improvement in blood sugar control.  It is known that it is not only by weight loss. Operations that were done in the past to help with weight loss that did not involve excluding or removing a portion of the gastrointestinal system did not show equal resolution of diabetes when matched for a percentage of weight loss. This information showed that weight and blood sugar have a complex relationship that remains to be fully understood.

Post-op Surgery and Long-Term Care

In current times, all of these operations can be done through small incisions. They usually are associated with a one or two-night hospital stay. Most patients go home feeling well and anxious to get back to their normal lives. 

Pain is minimal and they return to work in about two weeks. Most are discharged home without their diabetes medication. Bariatric surgery is a tool to help patients modify their lifestyle. To be successful, it requires changing long-time habits. The surgery itself is a tool to help the patient diet and achieve a calorie deficit. 

It is important for the patient to continue with proper exercise habits to build muscle mass. The choice of which surgery is appropriate for each patient is a decision that must be made after being well informed. The operations are very safe and are well-tolerated by most, but not without risk. Choosing the right operation for you is something that should be done after having all your information and discussing options and limitations with your surgeon.

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Gurdeep Matharoo


Dr. Gurdeep Matharoo is a Bariatric Surgeon at Community Medical Center in Toms River, NJ. Dr. Matharoo is a member of the American College of Surgeons, the American College of Surgeons New Jersey Chapter, the American Society of Metabolic and Bariatric Surgeons, the Society of Laparoendoscopic Surgeons and the Society of American Gastrointestinal and Endoscopic Surgeons. He holds medical licenses in both New York and New Jersey.