The average British person's near-total ignorance of their state of health is, of course, a cherished component of the national psyche - as essential as a fixation with climatic conditions, or never getting to the finals at Wimbledon. Every so often, though, comes statistical confirmation of the true depths of our ignorance - and the results still have the power to shock.
So it was with yesterday's report from the British Diabetic Association, revealing that an estimated 1m Britons suffer from diabetes without knowing it. As any of the 1.4m diabetics who do know of their condition will testify, this is not the sort of condition it's advisable to ignore: blindness, strokes, kidney damage and heart disease can result if it is not kept under control, and amputations can be required.
But that is not the limit of our ignorance: it also extends, the BDA says, to those at high risk of developing the disorder, three quarters of whom were not aware of the dangers, according to the survey of 2,135 people.
Almost all of the "missing million" will be suffering from type II diabetes, in which the body's natural mechanisms for regulating levels of sugar in the blood - normally controlled by insulin produced in the pancreas - become overwhelmed, usually because of obesity. Strict dietary controls and increased exercise are often enough to control the problem, and most sufferers can avoid the numerous daily insulin injections which are a depressing fact of life for type I diabetics.
But the popular perception that type II is less serious than type I - which usually develops in childhood when the body's immune system launches an assault against its own insulin-producing cells - is false. Left unattended, type II diabetes can be just as problematic. Although less common than among type-I diabetics, insufficient levels of glucose in the blood can prompt hypoglycaemic episodes, or "hypos", characterised by dizziness, confusion or aggression. Without prompt treatment, coma can ensue.
"This is an alarming state of affairs: these findings underline the myth many people believe - that dia betes can be a mild condition," said Paul Streets, chief executive of the BDA, which is to rebrand itself as Diabetes UK early next month. "It is not. Diabetes is one of the most serious health issues facing the UK today, and if society keeps on ignoring its importance we will be facing a potential health timebomb."
It is an overused term, but if any contemporary medical problem deserves the timebomb label, it is diabetes. Cases are expected to skyrocket, by 2010, to 3m in Britain and 220m worldwide. Already, the BDA estimates, the NHS spends £4.9bn on treatment annually; at any one time, diabetics occupy between 6% and 16% of Britain's hospital beds.
High-sugar, high-fat, low-fibre western diets must probably shoulder much of the blame for the proliferation of type II cases; some nutritionists blame the carbohydrates with which processed foods are stuffed, and which the pancreas strains to metabolise. But perhaps even more worryingly, the incidence of type I diabetes is increasing too, and the age at which children are affected is falling. And here - apart from some much-contested reports linking the disorder to the MMR vaccine - the causes are far more mysterious.
Indeed, the medical establishment's attitude towards the disorder can sometimes seem to rival levels of ignorance in the population as a whole. In April this year, an Audit Commission report exposed astonishing variations in the quality of care around the UK, with some doctors failing to undertake the basic checks that can prevent eye and liver-related complications. A third of hospital wards lacked adequate guidelines for managing the problem, the commission found.
At the forefront of medical science, breakthroughs are announced almost monthly, but diabetics are well used to riding the rollercoaster of hope and disappointment which has characterised the field ever since the first injections of insulin into humans, in 1924.
A couple of years ago, the headlines were full of Rezulin, a tradename for troglitazone, which helps reawaken type II diabetics' sensitivity to insulin - but it was withdrawn in the UK amid fears over side-effects. (A rival drug, Avandia, is now available.) Insulin nose sprays, insulin tablets, pumps which drip insulin gradually into the bloodstream, and insulin inhalers have all enjoyed brief moments of celebrity, but regulating dosage has proved difficult.
Two weeks ago came potentially the most promising news yet, when James Shapiro, a British surgeon from the University of Alberta in Canada, announced that he had managed to transfer the cells which generate insulin in non-diabetics into the bodies of severe type I sufferers who had previously been "crashing their cars, falling off horses or burning themselves while cooking". All, according to Shapiro, were now able to live normally, so long as they took immunosuppressant drugs to prevent their bodies rejecting the cells.
But it will take more than headlines to convince those who live with the problem that a solution really is around the corner.
"My daughter has had diabetes since she was five. That was 25 years ago, and I've listened to this for 25 years, which does make one a bit cynical," says Jenny Hirst, co-chair of the Insulin Dependent Diabetes Trust, formed in 1994 in protest at the BDA's controversial decision to withhold a report on the alleged dangers of synthetic insulin, used by some diabetics as an alternative to traditional insulin derived from animals.
"Take this latest announcement. The test subjects all had extremely severe diabetes, untreatable with insulin. But if you're an average sufferer, the choice is: do you want to go on immunosuppressants for the rest of your life, or do you want to carry on taking insulin? That's not much of a choice, and I think many will prefer to continue with the regime they know."
Basic screening procedures, rather than futuristic contraptions and cutting-edge innovation, may prove more effective weapons in the short term. Campaigners propose a national programme of urine tests for over-40s visiting their GPs - a low-cost exercise similar to blood-pressure monitoring programmes that would help identify those at risk at an early stage. That, and far more strenuous health education efforts. The existence of hundreds of thousands of unwitting sufferers, says Hirst, "has been known for years. It's just extremely sad that we don't seem to have made any progress."
Untreated diabetes: what to look for
Early symptoms of untreated diabetes include:
frequent need to go to the toilet
tingling or numbness in hands or
cuts and bruises that are slow to
erection impairment in men and
unusual vaginal dryness in
The risk groups
Those most at risk of type II diabetes belong to two or more of the following groups:
those with a family history of the
Asian and AfroCaribbean people.
The British Diabetic Association (Diabetes UK): 020-7323 1531
Insulin Dependent Diabetes Trust