Obesity is fast becoming one of the largest drains on NHS resources. In February 2011, a report issued by the NHS Information Centre (2011a) suggested that the number of obesity-related hospital admissions rose by 30% in 2010. The majority of these hospital admissions are secondary to conditions such as hypertension and diabetes. According to NICE, the annual cost to the NHS of obesity and related illness is £4.3 billion (Office of Health Economics, 2010), and leading UK surgeons believe that following NICE guidance on selecting individuals for bariatric surgery could save the NHS up to £56 million per annum (Office of Health Economics, 2010).
NICE (2006) guidance recommends bariatric surgery as a treatment option for people with obesity if all of the following criteria are fulfilled:
- They are ≥18 years of age.
- They have a BMI of 40 kg/m2 or more, or between 35 kg/m2 and 40 kg/m2 and other significant conditions (for example, type 2 diabetes or high blood pressure) that could be improved if they lost weight.
- They are or will be receiving intensive management in a specialist obesity clinic at a hospital.
- They have tried all other appropriate non-surgical treatments to lose weight but have not been able to maintain weight loss.
- They have no other specific medical or psychological reasons why they should not have this type of surgery.
- They are generally fit enough to have an anaesthetic and surgery.
- They understand that they will need long-term follow-up by a doctor and other healthcare professionals such as dietitians or psychologists.
Operative interventions
The antidiabetes effects of bariatric operations are due to decreasing insulin resistance and increasing the efficiency of the pancreatic secretion of insulin and the decrease of tissue inflammation (Cummings et al, 2004).
Operations can be divided into restrictive and malabsorptive categories. The gastric band is a purely restrictive operation, but most others have an element of both. The gastric sleeve is mainly restrictive as it removes a significant part of the stomach, but restricts gastric absorption of lipid-soluble substances such as alcohol, aspirin and non-steroidal anti-inflammatories. The gastric bypass and biliopancreatic diversion fit into both categories as they involve a gastric restrictive component, and a significant bypass of small bowel, which is the primary site of nutrient absorption. Estimates suggest that normoglycaemia is achieved in 48–72% of people after a restrictive operation (James et al, 2001) and over 80% of people after malabsorptive surgery (Dixon et al, 2005).
Intra-gastric balloon
Although strictly not a bariatric surgical operation (as it can be performed by any qualified endoscopist), the simplest form of bariatric intervention is the insertion of an intra-gastric balloon. A saline-filled balloon is placed endoscopically into the stomach, where it stays for 6 months before removal. This works simply by reducing the overall capacity of the stomach, but is the least effective of all procedures, with an average excess weight loss of 15–20% (Pinkney and Kerrigan, 2004). Although the amount of weight lost is often modest in comparison with the other commonly used bariatric procedures, any amount of weight loss is beneficial and contributes significantly to achieving good glycaemic control in obese people with diabetes.
Gastric band
The gastric band is one of the most commonly performed bariatric procedures. Its precursor, the vertical banded gastroplasty (VBG), is not adjustable, and is no longer routinely performed in the UK. People with VBG are often converted to a laparoscopic adjustable gastric band (LAGB) or bypass. The LAGB (Figure 1) involves placing an adjustable band around the proximal end of the stomach, creating a small pouch above it. As food is swallowed, the pouch fills, causing early satiety. Many studies report differing amounts of weight loss achieved; a review of the available meta-analyses focusing on gastric banding demonstrated an average excess body weight loss of 50–56% (Cunneen, 2008). Although gastric banding has a mortality approaching 0% and few immediate complications, long-term complications are more significant. The most common complication is band slippage – this is where the band slips down on the stomach, creating a much bigger pouch than originally intended, and causes vomiting and dysphagia. This occurs in 2–14% of cases (Chevallier et al, 2004). Erosion is another very significant complication, occurring 1–3% of the time (Suter et al, 2006). Up to 15% of people experience problems with their port or the port tubing (Abu-Abeid et al, 2003; Chevallier et al, 2004; Lattuada et al, 2007; Dixon et al, 2012) – for example, port rotation making access difficult, port infection or leaking tubing – although not all people with port problems require further surgery. Although weight loss can be significant, it requires a high level of patient adherence to be successful.
Sleeve gastrectomy
Unlike the gastric band, sleeve gastrectomy is irreversible as it involves stapling off and removing the greater part of the stomach, leaving a thin cuff of lesser curve (Figure 2). This works by restricting the capacity of the stomach, resulting in early satiety, but still allowing secretion of intrinsic factor and digestive enzymes. The malabsorptive effects are reduced although some surgeons still recommend long-term treatment with vitamins and B12 injections following this type of surgery. Traditionally, sleeve gastrectomy has been performed as a first operation to lose weight before converting to a gastric bypass or duodenal switch, although it is becoming more common as a stand-alone procedure. One systematic review demonstrated excess body weight loss ranging from 33–90% maintained for up to 3 years (Shi et al, 2010); another showed a mean of 47.3% at 13 months (Gill et al, 2010). Resolution of type 2 diabetes has been shown to range from 50% to 90% up to 3 years after the operation (Gill et al, 2010; Nosso et al, 2011), suggesting that this is an effective treatment for diabesity. Complications of sleeve gastrectomy include mortality and staple-line leak rates of between 1 and 3% (Vetter et al, 2009; Higa et al, 2011; Valezi et al, 2011). Some centres offer the sleeve gastrectomy as a first-line treatment for the morbidly obese individual, although this is often based on the surgeon’s preference and no general consensus exists as to which operation is “best”.
Biliopancreatic diversion with duodenal switch
Traditionally the biliopancreatic diversion with or without the duodenal switch was a commonly performed operation, but has lost much of its popularity in recent years. This is mainly due to the complication rates (Smith et al, 1996; Schauer et al, 2003; Sugerman et al, 2003; Wickremesekera et al, 2005; Farag and Gaballa, 2011) or consequential nutritional problems such as hypoproteinaemia, malabsorption and malnutrition (Evans and Scott, 2001). Hepatic impairment after these operations is also a well-documented consequence (Pories, 1992) that does not seem to occur in the gastric bypass, sleeve or band.
A mark is made on a segment of ileum approximately 60 cm from the ileocaecal valve, and the jejunum approximately 230–260 cm from the ileocaecal valve is transected. The proximal end is then anastomosed to the 60 cm mark. Performing a partial gastrectomy creates a small pouch of stomach and this is then anastomosed on to the free distal end of the transected jejunum. Although weight loss is significant, which makes the operation an attractive option for people with type 2 diabetes, complications can lead to other long-term problems that may in themselves contribute to hospital admissions and morbidity. Although no systematic reviews specifically detail biliopancreatic diversion or duodenal switch in terms of diabetes resolution, studies have shown an improvement in glycaemic control in close to 100% of individuals (Lifante and Inabnet, 2008; Mingrone and Castagneto, 2009).
Laparoscopic Roux-en-Y gastric bypass
The laparoscopic Roux-en-Y gastric bypass (Figure 3) is a highly successful operation in terms of diabesity treatment. The stomach is divided to create a small pouch and a further division is made approximately a metre along the small bowel (although length is variable according to the surgeon’s practice). The distal end of the small bowel is then anastomosed onto the remaining pouch of stomach. After measuring a further metre down the small bowel (again this length varies), the remaining cut end of the small bowel (which receives the stomach and duodenal contents including bile and pancreatic juices) is re-anastomosed at this point. Food content passes through the small pouch and then joins with digestive enzymes at the distal anastomosis. This has both a restrictive and malabsorptive component, unlike the sleeve or the band.
The physiological effects of the Roux-en-Y bypass can be summarised by the acronym BRAVE (Kresser, 2010):
- Bile flow alteration.
- Reduction of gastric size.
- Anatomical gut rearrangement and altered flow of nutrients.
- Vagal manipulation.
- Enteric gut hormone modulation.
Excess body weight loss after gastric bypass has been shown in systematic reviews to be 68–76% (Tice et al, 2008). One meta-analysis has shown a trend towards an increase in excess weight loss with a longer Roux-en-Y limb that suggests a benefit in super-obese people (Orci et al, 2011). Early remission of diabetes following gastric bypass has been shown to be as high as 83% (Cossu et al, 2004). By altering the physiological function of the foregut in this manner, the action of insulin is improved and glucose metabolism altered (Michielson et al, 1996). In many cases, the authors’ unit’s practice is to stop insulin in post-bypass patients immediately after surgery because of the success of this procedure in helping to control diabesity. Most people continue their metformin, although they must be monitored closely post-operatively in order to see a change in blood glucose.
Gastrointestinal liners
A gastrointestinal liner (such as the EndoBarrierTM [GI Dynamics Inc, Lexington, MA, USA]) is an endoscopically placed implant that has the effect of mimicking an intestinal bypass (Figure 4). A sleeve is deployed that sits in the first 60 cm of jejunum secured in place with a metal anchor, blocking absorption of food. Cheaper than the gastric bypass, it also has the advantage of being reversible. As of 2010, a UK trial was recruiting people for the EndoBarrier technology, to confirm its efficacy in the general UK population. Although the results of this trial have not yet been made available, another prospective non-randomised study demonstrated a mean weight loss of 20.4 kg at 1 year and a decrease in HbA1c from 73 to 46 mmol/mol (8.8 to 6.4%). All diabetes medications with the exception of metformin were reduced, and in two people these were stopped altogether (De Moura et al, 2011). Although these results seem promising, only 22 people were recruited and nine people had early removal of the EndoBarrier due to device migration or other complications. The results of the larger UK study involving 60 people will provide further data.
Discussion
A report estimated that £9 billion, or 10% of the total NHS budget (Hex et al, 2012), is spent on treating diabetes and its complications, and that 4.3% of the UK’s population in 2009/10 had diabetes (NHS Information Centre, 2011b). This number is thought to be increasing rapidly and, as a result, the number of hospital-related diabetes admissions are rising. Projections from the World Health Organization (WHO) estimate that by 2030, approximately 366 million people worldwide will have diabetes (Wild et al, 2004) and Diabetes UK (2010) statistics estimate that this number will include more than 4 million of the UK’s population. Not all cases of diabetes are related to obesity, but an increased BMI is a well-known precursor of the condition. In fact, many of the glucose and insulin abnormalities that are found in diabesity are also found in obese people without diabetes (Scopinaro et al, 1998).
Therefore, diabesity is a topic that has recently been the subject of much discussion by the WHO (2012) and the International Diabetes Federation (IDF; 2012). People with diabesity often have a number of issues including abdominal obesity, hypertension, dyslipidaemia (low high-density lipoprotein cholesterol levels, high low-density lipoprotein cholesterol levels and high triglyceride levels), and high blood glucose level (HbA1c <37 mmol/mol [<5.5%]). There is also a tendency to form thrombus, and a generalised systemic inflammation. This inflammation is significant in that it can be a precursor to weight gain. Infusion of inflammatory cytokines into normal healthy rats causes insulin resistance (Yu et al, 2002), and therefore perhaps by measuring these levels of cytokines, future weight gain in humans could be predicted. Inflammation begins in the fat cells – as these cells undergo hypertrophy, they become more inflamed and more resistant to insulin
Estimates suggest that in 2011, nearly a quarter of the UK’s population (22% of men and 24% of women [IDF, 2012]), had reached a BMI of >30 kg/m2, which is the clinical definition of obesity. NICE guidance suggests that people with a BMI of >40 kg/m2, or 35–40 kg/m2 with a significant obesity-related comorbidity (including diabetes or hypertension), are eligible for surgical treatment on the NHS. Worldwide, estimates suggest that 44% of the diabetes burden is attributable to obesity and being overweight (WHO, 2012).
As with any new diagnosis of type 2 diabetes, initial management should be lifestyle modification and weight loss. In some circumstances, weight loss can completely reverse insulin resistance. Some authorities believe that for the severely obese person, especially with concurrent diabetes, bariatric surgery should be offered almost as an initial treatment (Van Nieuwenhove et al, 2011), as dietary weight loss is often not as quick, nor as effective and recurrence of weight gain is more common. Bariatric surgery “enforces” weight loss whereas simple modification of lifestyle relies on the individual adhering to their weight-loss regimen (James et al, 2001). Other studies suggest that there is a relationship between the length of time a person is obese, and their likelihood of developing hypertension or diabetes; therefore the sooner someone is offered bariatric surgery, the more beneficial it will be to their health (Abu Abeid et al, 2003). A study by Sjöström et al (2012) showed that, when compared with a cohort of obese people not undergoing surgery, mortality was decreased in those who had undergone surgery, primarily because of reduced cardiovascular deaths.
Bariatric surgery has become increasingly advanced over the past few decades, especially since the introduction of laparoscopic surgery. Safety and efficacy has improved dramatically and it is becoming a much more reliable alternative for those with obesity. Those with diabesity may reap the most benefit; long-term studies have shown a significant benefit in reduction of diabetes (James et al, 2001; Suter et al, 2006; Mittermair et al, 2009; Van Nieuwenhove et al, 2011). One study showed that, in fact, out of 165 patients, 82.9% remained in remission from their diabetes after a mean follow-up of 14 years (Pinkney and Kerrigan, 2004). The benefits of improved glycaemic control can be seen fewer than 6 days after surgery (Suter et al, 2006), and to a lesser extent, there is an improvement in beta-cell function (James et al, 2001).
The follow-up of individuals after bariatric surgery varies between hospitals and is often up to the individual unit. Initial follow-up usually occurs approximately 4–6 weeks post-surgery and then at regular intervals. At present in Sheffield, patients are followed up in hospital for 2 years and then discharged to primary care where possible. More frequent follow-up may be required in some people, especially those with gastric bands. Follow-up in this initial period is important to monitor weight loss, nutritional status, and glycaemic control.
Specialist dietitians are often part of the bariatric unit and they have expertise in monitoring the nutritional and diabetes aspects of bariatrics. Individuals are advised to return to the diabetes clinic either at the hospital or at their GP practice, and to contact their diabetes specialist nurse on discharge from hospital. Individuals that have been treated with insulin for their type 2 diabetes for more than 5 years before surgery are often given metformin and low-dose insulin until they have lost a significant amount of weight and their glycaemic control returns to normal.
Conclusion
In obese individuala in whom medical management of their diabetes is unsuccessful in controlling their hyperglycaemia, or in the morbidly obese (BMI >35 kg/m2), bariatric surgery may be a viable and effective treatment and both primary and secondary care practitioners should be aware of its success in treating diabesity. Early referral to a bariatric clinic would allow the individual access to weight-loss seminars, dietitians, psychologists (who have an active role in the management of obesity, particularly for individuals who binge eat), diabetologists and surgeons. The earlier a person with diabesity loses weight, either by medical or by surgical means, the less time there is for them to develop the complications of type 2 diabetes such as retinopathy, nephropathy and neuropathy, and hypertension, atherosclerosis and peripheral vascular disease (Mittermair et al, 2008). This, ultimately, will be beneficial not only to the individual in terms of morbidity and life expectancy, but also, significantly, to the health services throughout the UK.
