04 May Diabetes: In The Blood
Type 1 diabetes is the most common form of diabetes in childhood, and while not preventable, it can be treated and managed, writes Dr Sam Tormey.
As I watched the small digital display of the portable blood-glucose machine in my hand, it struck me that there are not many times in a medical career when a single number can mean so much to a patient. I still had 10 seconds before the device would flash up a reading of the amount of glucose contained in the single drop of blood that I had dripped carefully onto the measuring stick. Eight seconds to go, and I looked across the room at the child from whom the blood had come. She was 11 years old, and looked exhausted. Her parents had brought her to the hospital, worried that she had a urinary-tract infection. For several days she had been weeing much more than usual, was off her food and had been complaining of fatigue and of being thirsty. Six seconds to go. I did not like the way that Emily* was breathing. She was taking deep, regular breaths although she was lying quite still on the bed. She didn’t have a cough or asthma. Four seconds to go. Something else was bothering me – Emily had mentioned something about her eyes being “funny” today, stating that she couldn’t see as clearly as usual. Two seconds to go, and I already knew that the glucose reading was not going to be normal. I was preparing myself to give Emily and her parents some bad news. The machine beeped as a number appeared – 28. A number that would mean a whole new world for Emily and her family.
Unbeknown to Emily, her pancreas had been producing smaller and smaller amounts of the hormone insulin over the last few months. Her symptoms over the last few days represented the final phase of the failure of her pancreas in this crucial role. Insulin regulates the entry of glucose from the bloodstream into the various cells of the body and is crucial to life. When the pancreas fails to secrete insulin, glucose levels in the blood start to rise. Emily’s blood-glucose level should have been between about four and eight millimoles per litre (the standard unit for measuring glucose in the blood), rather than 28, and her symptoms could all be attributed to this high reading. As her cells were not able to use glucose for energy, her body had switched to metabolising compounds called ‘ketones’. This leads to an excess of acids in the blood, which the body attempts to remove by ‘blowing off’ carbon dioxide – hence Emily’s unusual, deep breathing. The blurred vision that Emily reported can be attributed to changes in the fluid of the eyes and the lens due to all the excess, unmetabolised glucose moving around the body. As the kidneys excrete the glucose, some water is dragged with it, causing increased urination, subsequent dehydration and a thirst that cannot be quenched. This metabolic upset affects all parts of the body and is known as ‘diabetic ketoacidosis’.
Consult your GP if your child has any of the following symptoms and is not improving:
- unexplained lethargy and fatigue;
- excessive drinking;
- excessive urination;
- weight loss despite increased appetite; or
- unexplained nausea, vomiting or abdominal pains.
Patients in Emily’s predicament will become sicker and sicker, as the pancreas simply can no longer produce enough insulin. Had Emily been left untreated, the fatigue and nausea she was experiencing would eventually have progressed to confusion, coma and death. Instead, shortly after the machine had beeped out the number 28, Emily was receiving her first injection of insulin and lots of replacement fluids. A few hours later, she felt much better as her body returned to a more normal metabolism.
Put this way, the whole process seems simple: problem, diagnosis and successful treatment. Diabetes is, however, a far from simple condition, that requires complex and constant management – something that is not always reflected in public perceptions. The word ‘diabetes’ used to be synonymous with needles and people carrying around bananas or jelly beans in their pockets. These days, the word is more likely to be connected to obesity, poor diet, lack of exercise and a general sense of people not looking after themselves.
Diabetes mellitus, to use the full name of the condition, is derived from both Greek and Latin words and refers to the excessive amounts of sweet-tasting urine produced by untreated sufferers. Yes, doctors in the past would dip their finger in the urine and taste it – bless those clever digital machines we have now. Excess glucose in the blood and urine is really the end point of several diseases with quite different causes, and the shared terminology has caused a great deal of confusion between the two main types of diabetes. Type 1 diabetes accounts for about 10 per cent of cases, but it is the most common form of the illness in childhood and is the focus of this article. Type 2 diabetes accounts for about 90 per cent of cases and is much in the news at present. It is a disease characterised by a resistance to insulin, which is still produced in sufficient quantities by the pancreas. Although generally a disease of adults, type 2 diabetes is increasingly seen in children, almost certainly as a result of changing lifestyle and weight patterns. An unfortunate side effect of the very important health messages about type 2 diabetes is that type 1 diabetes might also be seen as a preventable illness.
Type 1 diabetes is not preventable (yet) and is not associated with excess weight, low exercise levels or poor diet.
Enormous efforts have been directed towards finding a cause for type 1 diabetes, but clear answers have eluded researchers. We do know that the failure of the pancreas is due to damage inflicted by the patient’s own immune system over months or years prior to the first symptoms. We also know that some people are genetically predisposed to this auto-immune attack, however, the trigger for the attack is unclear. As the illness is increasing at the rate of about three per cent per year in Australia, it would appear that we are being exposed more and more to whatever it is that starts the antibody attack on the special insulin-producing cells in the pancreas. Researchers are looking at many possible culprits, including viral infections, toxic chemicals, levels of vitamin D, proteins in cows’ milk, and several others. The role of common viral infections seems to be central, and some researchers have invoked the so-called ‘hygiene hypothesis’ as a possible factor. This theory, which has also been central to our thinking about the rising rates of asthma and allergies, proposes that our relatively recent changes to basic hygiene have resulted in fewer common infections. It may be the case that our immune systems, primed by evolution to deal with many more infections than we now contract, may react abnormally to a simple virus and inflict ‘collateral’ damage to organs such as the pancreas.
Knowing more about the possible causes of diabetes is crucial to efforts to prevent or cure it, for although insulin treatment is very successful, it is a daily occupation. Emily’s first insulin injection was the start of a regime that cannot be ignored or forgotten for more than a few hours at a time. In this sense, diabetics are the true tightrope walkers in our community. Too little insulin and there is the risk of high glucose levels and ketoacidosis. Too much insulin can cause low glucose levels which are more immediately dangerous than high levels, with fits and coma ensuing if levels are not rapidly raised (hence the jelly beans that diabetics may carry in their pockets). These are the short-term, daily concerns of patients like Emily. Walking the tightrope between low and high blood sugar affects long-term health as well: every time a diabetic has a ‘wobble’, falls off and ends up in hospital, damage is being done to the nerves, arteries, eyes and kidneys, and problems with these organs can appear later on in life. Indeed, even for those who don’t fall off the tightrope, but are leaning towards the high side of blood glucose for long periods, there are risks of serious damage in the longer term. Kidney failure, retinal problems, heart attack and stroke are seen commonly in patients who have had poorly controlled diabetes.
Such daily vigilance is a difficult burden for diabetic children and their families. Emily and her parents expected to go home from the hospital with a script for antibiotics, not a diagnosis involving daily medication and a whole team of health professionals to consult on a regular basis. Emily now sees her GP, a diabetes specialist, a psychologist, a diabetes educator and an ophthalmologist to keep her diabetes and her general health in good order. Simply understanding the diagnosis is hard enough at her age. But then there are the emotional reactions to receiving such news. She is doing well, but I did see her after another ‘wobble’ that demonstrates just one of the difficulties of adjusting to life with diabetes: she went on a snorkelling trip with some friends, but missed her lunchtime insulin injection because she didn’t feel comfortable injecting herself in front of everyone on the boat. The combination of a bit of sunburn, lots of exercise on a hot day and rising blood sugars meant that Emily was in hospital on an infusion of insulin for 48 hours.
Some kids like routine, some kids hate it.
For children with diabetes, routine is the key to maintaining good health. Regular sleep, eating and exercise habits are the best way to avoid wobbles. Exciting things such as birthday parties, sports carnivals, holidays and sleepovers can all upset the applecart, as can mundane things such as infections and injuries. Despite this, diabetic kids can lead utterly normal lives if they always keep the question ‘how will this affect my blood sugar?’ in mind.
Insulin treatment began in 1922, when Canadian doctors injected 14-year-old Leonard Thompson with an extract of pancreas from a calf. Leonard nearly died from an allergic reaction to the extract, but with a purified version he lived to the age of 27. Prior to this new treatment, most children with diabetes would die within a year of diagnosis. With more sophisticated versions of insulin and better management of the complications of diabetes, patients like Emily have a near-normal life expectancy – on average about five to 10 years short of that for a non-diabetic. But even the best treatment in 2007 still requires daily monitoring of the blood glucose and daily injections of insulin.
Research efforts are being directed at reducing this burden.
It seems natural that if the pancreas has failed, it could be replaced with a transplanted pancreas. This has been successfully attempted. However, as with other forms of organ transplantation, there are not nearly enough donor organs to meet the demand. Transplantation of just the insulin-producing ‘islet’ cells from a healthy pancreas has been conducted since 1990 and shows considerable promise. However, in both forms of transplantation, the patient must take powerful immunosuppressive drugs and many patients, for various reasons, have had to recommence treatment with insulin months or years after the transplant. The transplantation of stem cells that can turn into islet cells inside the recipient’s liver has shown great promise in diabetic mice, but there are many safety and ethical issues that must be addressed before large-scale trials in human patients begin. Readers might remember that type 1 diabetes featured prominently in the debate over stem-cell legislation a few years ago, with the (then) NSW premier, Bob Carr, becoming a strong advocate for the research after meeting a group of diabetic children.
Since type 1 diabetes is an auto-immune disease, the other main area of research has been in the field of immunology. Scientists in Melbourne are trialling a vaccine that aims to prevent type 1 diabetes in people at high genetic risk of the condition (at this stage, this means close blood relatives of people who already have type 1 diabetes). The vaccination process consists of sniffing small doses of insulin via a nasal spray and aims to modulate the immune response to the trigger that causes the damage to the pancreas.
Whether the future of diabetes lies with prevention (via a vaccine) or cure (via successful transplantation therapies), for the foreseeable future we must rely on replacement with insulin. A large US study of people with type 1 diabetes, the Diabetes Control and Complications Trial, confirms that tight control of diabetes in childhood has great benefits for health in adult life. This seems to be especially important for patients Emily’s age (11) and up. For a teenager, this might consist of three or four doses of insulin per day, and checking the blood glucose three or four times. That is an intense regime for a child, who may be tempted to let the readings run a bit high, rather than risk an embarrassing ‘hypo’ (hypoglycaemic or low-blood-glucose episode). Until we have a better way of treating diabetes, the best we can do for people like Emily is to support them and their families, encourage healthy routines and, as they get older, empower them to be the main managers of their condition. And as both main types of diabetes are on the rise, we need to support Australian researchers who are doing great work to try to improve the future health of diabetic patients.
* Emily is not my patient’s real name, however I have obtained her and her family’s permission to tell some of her story.
Diabetes Australia is a leading charity that raises community awareness of diabetes and funds for diabetes research and has member organisations in all States. It is also a great resource for all kinds of information on diabetes. Visit – http://www.diabetesaustralia.com.au
Dr Sam Tormey is a doctor who writes on medical issues.
Note: This article provides general health information and in no way constitutes medical advice. Ideas and information expressed may not be suitable for everyone. Readers wishing to obtain medical advice should contact their own doctor.