Type 2 Diabetes is currently among the most common lifestyle disorders globally and one of the major risk factors responsible for this is obesity. Multiple studies have proven this thing in the past that high body fat percentage increases the risk factor for type 2 diabetes and if it goes uncontrolled, can lead to blindness, amputation of the foot, and kidney failure. Multiple treatment modalities are in the picture as of now including medical therapies but there is no permanent solution to cure this disease.
Current medical therapies are aimed to lower blood sugar levels and insulin resistance associated with type 2 remission of diabetes. Bariatric surgery has been recognized as a potential treatment for obesity and associated risk factors, including type 2 diabetes.
In 1980, during a clinical trial of Greenville gastric bypass (bariatric surgery), first time remission of type 2 DM was noticed post-surgery and since then multiple researchers have proven its efficacy as a successful modality to manage blood sugar levels. In 2016, the Second Diabetes Energy Summit (DSS-II) recommended bariatric surgery as a treatment for type 2 DM for adults with a BMI >40 or >35 kg/m 2 with obesity-related risk factors.
Surprisingly, the drop in blood glucose levels post-surgery happens within hours to days and precedes weight loss, thus suggesting that the desired results are not solely because of weight loss but also because of the altered flow of intestinal contents. The most commonly performed bariatric surgery being performed is Roux-en-Y Gastric Bypass (RYGB).
Mechanism of Remission
One of the most common theories explaining the mechanism implicates the anterior part of the gut (foregut; from mouth to the duodenum) as a contributing factor. When foregut diversion occurs, as in the case of RYGB, glucose levels improve. Different techniques of bariatric surgeries have shown that more is the diversion of foregut, much better is the glycemic response thus suggesting the integral role of distal stomach and duodenum.
As per one of the studies, oral glucose intake compared to equivalent intravenous load inhibits glucagon secretion. This study observed that there is a group of hormones (incretin family of hormones – GLP 1 and GIP) that are secreted by the gut that has a significant effect on beta-cell production of insulin, glycogenolysis, insulin resistance, and gluconeogenesis. Then there are also anti-incretin hormones secreted by the gut that affect insulin production and also increase insulin resistance. In the case of RYGB, the foregut diversion occurs and this unstimulated foregut fails to release anti-incretin hormones and this improves the blood sugar levels.
Some studies have also shown the alteration in hormones like ghrelin, leptin, cholecystokinin that may impact the feeling mechanism via the gut-brain axis.
Safety and Efficacy
The long-term benefit from bariatric surgery depends upon factors like the type of surgery performed, comorbidities, patients’ readiness for lifelong dietary modification, maintenance of lost weight, and constant follow-up. While the surgery is proven to be safe and effective, it comes with its own set of challenges. The complications rate can be as high as 21% in RYGB cases with a mortality rate of 0.35-0.79%. Complications include hemorrhage, postoperative readmission, need for reoperation, postoperative hypoglycemia, acid reflux, ulceration, and micronutrient deficiencies.
Apart from this, this surgical procedure comes with a huge financial burden as well. So, all the pros and cons need to be assessed before planning for the surgery.
Recommendation for surgery
As per the 2016 recommendation, a patient who can qualify for bariatric surgery has to show at least 6-months of unsuccessful attempts at weight loss using traditional dietary and exercise advice. This is also done to assess the commitment of the patient towards a healthy lifestyle that is being needed in the long run. As per one of the studies, weight loss is the major determinant of return to normal sugar levels post-surgery. Short-duration remission might be because of change in intestinal flow and incretin group of hormones but long-term results depend upon weight loss.
Calorie Restriction Vs Bariatric Surgery
The mechanisms regarding the remission of type 2 DM is quite clear after multiple studies that are reduction in weight and thus body fat percentage and most importantly the lifelong commitment to a healthy lifestyle. It means calorie restriction can alone serve as a driver for the remission of type 2 DM. Studies have also shown that RYGB surgery along with calorie restriction has no added advantage over weight loss in the long term thus indicating that incretin hormones may not be the primary mechanism as suggested before.
Even after surgery, an alarming number of patients experience weight regain and recurrence of obesity-related conditions including type 2 diabetes. In these patients, lifelong dietary intervention is more important.
To conclude, bariatric surgery can be an effective treatment modality to manage blood glucose levels but it comes with its own set of pros and cons. Also, if someone is not looking to change his/her lifestyle and maintain healthy eating habits, even bariatric surgery won’t be able to help with the remission of type 2 DM. So, before someone opts for the surgical option, they have to make sure they are committed to a long-term lifestyle modification.
Reference list
- Hallberg, S.J., Gershuni, V.M., Hazbun, T.L. and Athinarayanan, S.J. (2019). Reversing Type 2 Diabetes: A Narrative Review of the Evidence. Nutrients, [online] 11(4), p.766.
- Pories, W.J., Mehaffey, J.H. and Staton, K.M. (2011). The surgical treatment of type two diabetes mellitus. The Surgical Clinics of North America, [online] 91(4), pp.821–836, viii.
- Rubino, F. and Gagner, M. (2002). Potential of Surgery for Curing Type 2 Diabetes Mellitus. Annals of Surgery, 236(5), pp.554–559.
- Rubino, F., Nathan, D.M., et al. (2016). Metabolic Surgery in the Treatment Algorithm for Type 2 Diabetes: A Joint Statement by International Diabetes Organizations. Diabetes Care, 39(6), pp.861–877.
- Steven, S., Carey, P.E., Small, P.K. and Taylor, R. (2014). Reversal of Type 2 diabetes after bariatric surgery is determined by the degree of achieved weight loss in both short- and long-duration diabetes. Diabetic Medicine, 32(1), pp.47–53.
