Diabesity – Weight Loss Surgery offers complete resolution for most patients
by Dr David Ashton MD, PhD
It is precisely because of the dramatic impact of obesity surgery on type II diabetes that in 2007, the highly respected and authoritative American Society for Bariatric Surgery, changed its name to the American Society for Metabolic and Bariatric Surgery (ASMBS). The Society’s president, Dr Kelvin Higa, put it succinctly:
“Surgery for severe obesity goes way beyond weight loss. This surgery results in the complete remission or significant improvement of type II diabetes and other life-threatening diseases in most patients. The Society’s new name and mission reflect this”
Before we look at individual surgical procedures and their likely impact on diabetes, it’s useful to describe the two main types– Type I and Type 2.
Type 1 Diabetes
Type 1 diabetes develops when the insulin-producing cells (β cells) in the body have been destroyed. Insulin acts as a key which unlocks the body’s cells allowing glucose (sugar) to enter where it can be used as fuel. In Type I diabetes the body is no longer able to produce insulin and so glucose accumulates in the blood.
Type 1 diabetes can develop at any age but usually appears before the age of 40, and especially in childhood. It accounts for between 5 and 15 per cent of all people with diabetes and is treated by daily insulin injections, a healthy diet and regular physical activity.
Type 2 Diabetes
Type 2 diabetes develops when the body can still make some insulin, though not enough, or when the insulin that is produced does not work properly (known as insulin resistance).
Type 2 accounts for 85-95% of all diabetics and usually appears in people over 40, though in South Asian and black people, who are at greater risk, it often appears from the age of 25. It is also becoming increasingly common in children, adolescents and young people of all ethnicities. It is commonly treated with diet and medication, though in more severe cases insulin may also be required.
Weight Loss Surgery and Type 2 Diabetes
All surgical weight loss procedures have a beneficial impact on type II diabetes, though the mechanisms underlying these effects may be very different. The main procedures and their effects on diabetes are discussed briefly below.
Most of the recent evidence shows that the gastric band will result in complete resolution of diabetes in approximately 40-75% of those undergoing gastric banding2-4. The probability of complete cure of the diabetes appears to be related to the length of time for which the patient has been diabetic. When the disease has been present for less than three years, there is a greater likelihood of a cure.
Most of the effect of the gastric band on diabetes is related to the amount of weight loss; as weight loss improves with time, the impact on the diabetes also becomes more marked. In addition, a recent study showed the beneficial effects of the band on diabetes are sustained at 5-years follow-up4.
Studies show that around 80-85% of gastric bypass patients will experience complete resolution of type 2 diabetes1,3. However, whereas with the gastric band the improvement is related to the amount of weight loss, the gastric bypass has a dramatic and almost immediate effect on type 2 diabetes, independent of weight loss. For example, individuals who are on insulin will often stop their insulin injections within 48-hours of the surgery – well before any significant weight loss occurs. It’s not entirely clear how this happens, but it appears to be related to changes in certain gut hormones – including ghrelin – which are involved in insulin and glucose regulation. Whatever the mechanism, the impact on diabetes is dramatic.
Sleeve gastrectomy is a relatively new procedure, which is rapidly gaining popularity. The impact on type 2 diabetes is almost identical to that of gastric bypass, i.e. around 80-85% resolution5,6. Precisely how this happens is unclear, though as with gastric bypass it is likely to involve a range of gut hormones, including ghrelin.
Biliopancreatic Diversion/Duodenal Switch is a major surgical weight loss procedure, usually reserved for those with a BMI of >60kg/m2. It’s impact on type 2 diabetes is greater than that of any other surgical procedure, leading to complete cure in around 95% of cases1,3. Unlike other weight loss procedures such as gastric bypass, BPD/DS is a true malabsorptive procedure, leading to substantial and sustained weight loss. However, without careful nutritional support, including vitamin and mineral supplementation, adverse effects such are anaemia, bone disease and nerve damage, can occur. Nevertheless, the impact of this procedure on type 2 diabetes is both dramatic and sustained.
Weight Loss Surgery and Type 1 Diabetes
Compared with type 2 diabetes, surprisingly few studies have addressed the effect of weight loss surgery on type I diabetes. However, clinical experience suggests that even though a true cure is more difficult to achieve in type 1 diabetics, surgery invariably results in better diabetic control which would, in the longer term, reduce the risk of diabetic complications.
One recently published study examined the effect of gastric bypass on three patients with established type I diabetes7. All three patients experienced a remarkable improvement in their diabetic control, as well as in blood pressure and cholesterol levels. These changes will undoubtedly reduce the risk of long-term complications from heart and other diabetes-associated diseases.
1. Dixon.JB. Obesity and Diabetes: The Impact of Bariatric Surgery on Type-2 Diabetes. World J Surg 2009; 33:2014-2021
2. Sultan S, Gupta D, Parikh M et al. Five-year outcomes of patients with type 2 diabetes who underwent laparoscopic adjustable gastric banding. Surg Obes Relat Dis 2010; 6: 373-6
3. Buchwald H, Avidor Y, Braunwald E et al. Bariatric surgery: a systematic review and meta-analysis. JAMA 2004; 292: 1724-1737
4. Dixon JB, O’Brien PE, Playfair J et al. Adjustable gastric banding and conventional therapy for type 2 diabetes : a randomized controlled trial. JAMA 2009; 299: 316-323
5. Basso N, Casella G et al. Laparoscopic sleeve gastrectomy asa first stage or definitive intent in 300 consecutive cases. Surg Endosc 2010; July [Epub ahead of print].
6. Abbatini F, Rizzello M, Cassalla G et al. Long-term effects of laparoscopic sleeve gastrectomy, gastric bypass and adjustable gastric banding on type 2 diabetes. Surg Endosc 2010; 24: 1005-10
7. Czupryniak L, Wiszniewski M, Szymanski D et al. Long-term results of gastric bypass surgery in morbidly obese type 1 diabetic patients. Obese Surg 2010; 20:506-8