According to the NHS, there are more than three million people in the UK with diabetes. Factoring in the estimated 850,000 who don’t realise they have it, around one in 20 Brits is diabetic. By 2030, the number of patients is expected to rise to 4.6 million, with type 2 diabetes, a condition commonly associated with obesity, accounting for 90% of cases. It’s a situation the normally reserved BBC has labelled "an epidemic".

As well as the severe implications diabetes has for a person’s health, the monetary value of treating the disease is staggering. Around a tenth of the NHS’s budget is allotted to tackling it – £25,000 every minute, £1.5 million an hour. It’s costing the economy a combined £16.3 billion in absenteeism and early retirement, while society is also losing out on £152-million-worth of benefits.

And the problem isn’t UK-specific. WHO expects the number of diabetics worldwide to have doubled between 2005 and 2030, with many nations now actively exploring new ways to halt the rise in cases and treat the disease. Earlier this month, the US’s Preventive Services Task Force recommended that all adults aged over 45 be screened for diabetes, while the Health Consumer Powerhouse’s Euro Diabetes Index 2014 recently ranked each EU member state’s ability to tackle diabetes in order to see how countries stack up against each other and where improvements can be made.

In the UK, which ranked fourth on the list, bariatric surgery is already a recommended option for patients with type 2 diabetes and a BMI of over 35, as evidence suggests that 60% of patients who undergo the operation experience significant health improvements. And in a bid to counter booming disease numbers, the National Institute for Health and Care Excellence (NICE) has put forward proposals to offer surgery to those whose BMI breaches 30 and are therefore classified as obese.

It’s proved an especially divisive proposal. While NICE champions the patient health improvements, reduced long-term cost to the NHS and wider economic benefits, critics bemoan the strain the UK’s health service will come under from an influx of patients and the initial cost of funding it. There’s ample evidence to support the efficacy of using bariatric surgery to treat diabetes and induce weight loss, even if understanding the causes behind the phenomenon has required an element of revisionism.

The stomach for it

When bariatric surgery was first performed more than 50 years ago, it involved short-circuiting the bowel in order to provoke malabsorption, the idea being that a lower-calorie intake would result in weight loss.

The technicalities of the operation led to the unwanted creation of a blind loop of small intestine, and with time, it became apparent that a significant number of patients were falling ill, prompting surgeons to abandon the procedure. Research also suggested the reason for weight loss was due to reduced food intake and not malabsorption, as originally believed.

After a brief period where purely restrictive surgery – stapling the stomach to make it smaller – was adopted and subsequently dropped due to its apparent ineffectiveness, laparoscopic surgery took off, transforming weight-loss procedures and drastically reducing the risks of performing them. It gave rise to the use of the gastric band, now the most common form of bariatric surgery, where an inflatable silicone elastomer strap tightens the entry to the stomach, limiting the amount of food that can be eaten.

Operation mortality rates are less than one in 2,000, rendering the band reasonably safe to insert; however, although it’s proven to help patients lose weight, it’s not without its risks. Patients are still able to absorb calories that pass the band, such as alcohol, ice cream and fizzy drinks, while it also has a tendency to slip, constricting the stomach and causing acute necrosis – a medical emergency where the blood supply is cut off. The ratio for such occurrences is relatively low at one in 1,000, though it is more frequent in pregnant women.

Two other, now preferred, forms of bariatric surgery are the sleeve gastrectomy and the gastric bypass. The former removes most of the stomach, leaving a sleeve-like tube; the latter involves fashioning a small gastric pouch to which the intestine is connected so that food bypasses the duodenum and goes straight into the proximal intestine, limiting food digestion. Though the treatment was originally used for stomach ulcers in the 1950s, it inadvertently acted as a catalyst for dramatic weight loss among patients, originally thought to be a result of combined restriction and malabsorption.

"Just like the original bypass surgery, we now know that the reason this operation produces weight loss is not through these mechanisms," says Professor Nicholas Finer, consultant endocrinologist and bariatric physician at University College Hospital, London, who also chairs the World Obesity/Clinical Care organisation and acts as a governmental adviser on obesity.

"Most doctors have little training, skills or interest in managing obesity. The NICE guidance may be appropriate based on the evidence, but we actually have some quite significant logistical NHS capacity issues to consider."

"Firstly, when the stomach is isolated, levels of the hunger hormone ghrelin, which seems to initiate food intake, falls," he says. "Secondly, the food leaves the stomach remnant more rapidly, going straight into the intestine and releasing potent hormones like GLP1, which enter the brain and cause patients to feel fuller, faster. We also have to consider changes in gut flora and the diversion of bile that arise as a result of a reduced stomach capacity."

Not just nice to have

There are many forms of bariatric surgery, and the two most common types, the gastric band and bypass, have proved extremely effective treatments for type 2 diabetics. The procedures normally produce a 60-70% reduction in excess body weight, and observations suggest that 70% of patients can come off medication altogether.

"Most doctors have little training, skills or interest in managing obesity. The NICE guidance may be appropriate based on the evidence, but we actually have some quite significant logistical NHS capacity issues to consider."

"Whether it is cure or remission is really just semantics," says Finer, who has researched clinical aspects of obesity throughout his career, publishing a range of scientific papers and books on the topic. "The reason they can come off drugs is because of the increased circulation of GLP1, driving insulin secretion and suppressing appetite. With a large reduction in weight, you lose your insulin resistance, as you use up the fat stores that drive it. This effect has led some centres and surgeons to rename the operation ‘metabolic’, as opposed to ‘weight loss’, surgery."

While the patients benefit medically, health services and the wider economy stand to make financial gains from the NICE proposal. Each operation costs the NHS around £10,000, and analysis indicates that the procedures probably pay for themselves within three years once the dramatic reduction in drug and care provision is factored in, not to mention the added value each patient offers the economy through lower levels of absenteeism from work.

"They’re highly cost-effective – it’s why NICE has been recommending them for the past decade," says Finer. "Traditionally, bariatric surgery was recommended for patients with a BMI above 40, or 35 if they also had a weight-related problem, such as type 2 diabetes or hypertension. NICE even suggested that for those above [a BMI of] 50, it should be the first form of treatment.

"With the recognition of its exemplary safety record and efficacy in treating diabetes, NICE believes there is value in offering it to anyone classed as obese. It may be counterintuitive – we think of diabetes as a medical disease, so why would you treat it surgically? – but as it’s predominantly an endocrinal operation, the results speak for themselves."

Weighing up the costs

Apart from an element of sensationalist scaremongering from certain corners of the media, the long-term health and economic benefits are widely accepted and championed.

However, despite this, implementing such a programme will not be without its short-term difficulties. In terms of BMI, 62% of the UK’s population is overweight, and the NHS estimates that around a quarter is clinically obese. Opening up bariatric surgery to all obese diabetics would make around 1.5 million eligible, placing a considerable burden on an already strained health service.

"This is where we have concerns," says Finer. "It’s a major surgery and requires a very sophisticated set of skills, as well as follow-up care and monitoring. Most UK health centres are set up as surgical practices, and there is a huge deficiency of physicians like myself who specialise in obesity and related diseases. Most doctors have little training, skills or interest in managing obesity. The NICE guidance may be appropriate based on the evidence, but we actually have some quite significant logistical NHS capacity issues to consider."

Although a reduction in overall drugs and care still stand to lower the total costs, the surgery itself represents only a fragment of the overall care patients require. Prior to the procedure, they will need to work hard to get their diabetes under control, a task often requiring professional assistance. Afterwards, they need close monitoring to ensure they don’t develop deficiencies, and for those that have lost an excessive amount of weight, there may be considerable loose skin and the rarely met need for cosmetic surgery.

A small proportion of patients, 2-3%, also develop complications, including severe reactive hypoglycaemia, a condition that involves abnormally diminished levels of glucose in the blood that can result in seizures and requires emergency treatment. Other patients have developed profound anorexia after the surgery and become malnourished, while 5-10% also regain more than half the lost weight over time.

Aside from the initial strain on the NHS and its ability to cope with potential complications, there are tough economic factors to consider too.

"We don’t have enough information to know how to maximise or prioritise the benefits," says Finer. "For example, you could have a 28-year-old woman with a BMI of 30, who is fit and healthy aside from the fact she’s overweight and a threshold diabetic. The surgery would certainly normalise her weight, but at the moment, she costs the NHS nothing.

"Compare that with a 58-year-old man, a type 2 diabetic of eight years with multiple weight-related afflictions; the surgery would have a marked improvement on his life, and the savings to the NHS would be immediate and substantial. However, you could argue that he only has 15 years of life left compared with the woman’s 50. So, from a health economic perspective, where do you put the money?"

NICE’s proposals may offer comprehensive answers on how best to deal with the epidemic of type 2 diabetes and obesity in the UK, but they also create logistical and economic questions of their own – expecting the NHS to cope with the immediate influx of patients is naive and dangerous.

The lower the BMI of potential patients, the more diminished the operation’s impact on their quality of life. For Finer though, bariatric surgery remains the best option for a significant demographic group. "It is certainly not a panacea, but from my perspective, if you perform the procedure on severely obese patients, its effects are miraculous, and the transformation it has on their life profound," he concludes.