Diabetes mellitus: a case history

UNDERSTANDING YOUR FOOD<br /> the ultimate educational resource<br /> TEACHER NOTES<br /> <br /> teachers’ notes S4.1<br /> KS4 and above<br /> science and technology<br /> Timing - various<br /> This is an extension exercise; it<br /> could be a homework.<br /> Two pupil activity sheets S4<br /> accompany this activity.<br /> The case study is a true account<br /> of a colleague’s experiences.<br /> S4. A case history<br /> In this text-based activity pupils read a case history and carry out some<br /> literature research.<br /> None of the answers can be found on the sheet; all have to be<br /> researched.<br /> Answers to Pupil activity sheet S4:<br /> 1. Abnormal bloodglucoselevels, frequent in diabetes, can result in<br /> blurred vision. The technical term for the complications that can result<br /> from abnormal blood glucose isdiabetic retinopathy. Retinopathy<br /> generally has no obvious symptoms until it is well advanced. It is<br /> important, therefore, for diabetics to have regular (annual) eye<br /> examinations.<br /> Diabetic retinopathy affects the blood<br /> vessels supplying the retina (the light<br /> sensitive region of the eye). Blood<br /> vessels in this area may become<br /> blocked, leaky or grow haphazardly.<br /> This may eventually impair vision<br /> seriously and permanently.<br /> By drinking orange juice, Ms G<br /> was actually adding more sugar<br /> into her bloodstream hence<br /> exacerbating the situation.<br /> 2. In diabetes glucose levels in the blood rise. Eventually this glucose will<br /> reach a level where it cannot be reabsorbed back into the bloodstream<br /> in the kidney tubules. After thisthresholdlevel, glucose will begin to<br /> appear in the urine. Since glucose is removed from the body in solution,<br /> more water than normal will be lost from the body as the glucose is<br /> excreted. This tends to dehydrate the body with the response that the<br /> individual will feel thirsty.<br /> 3.hyperglycaemia - a higher blood glucose than normal. Symptoms<br /> include an increased thirst, increased frequency of passing urine, blurring<br /> of vision, nausea or vomiting, drowsiness, stomach pain, cold, dry skin,<br /> deep rapid breathing, sweet smell on the breath.<br /> hypoglycaemia - a lower blood glucose level than normal. Symptoms<br /> include hunger, sweating, trembling, tingling of the lips, palpitations,<br /> blurring of vision, irritability.<br /> 4. If a diabetic were to have an accident whilst away from home or on<br /> their own, it is important for other people who are trying to care for<br /> them to know that they are diabetic. Being diabetic can have<br /> important consequences for the use of drugs, anaesthetics, etc.<br /> 5. It may happen that a diabetic will suffer from mild hypoglycaemia (have<br /> a mild ‘hypo’) if meals are slightly delayed or if extra exercise than<br /> expected was taken. By having sweets, etc. handy, it is possible to<br /> quickly reverse the symptoms.<br /> Continued overleaf.<br /> <br /> teachers’ notes S4.2<br /> 6. Advice to diabetics:<br /> When travelling by aeroplane carry all the diabetic equipment in hand<br /> luggage as suitcases have been known to go missing. Also the<br /> luggage hold is not heated and insulin stored at too low a temperature<br /> may freeze and be inactive. Always take spares of everything including<br /> insulin. This will cover breakages or delays in returning home. Some<br /> countries will not be able to supply the exact type of insulin used in this<br /> country.<br /> Take extra food and snacks in hand luggage in case meals are missed.<br /> In very hot climates special arrangements may have to be made to<br /> store insulin in a cool place.<br /> Sugar free drinks may be difficult to get in some countries.<br /> Meals should not really be a problem but it may be wise to check<br /> with a dietician before travelling.<br /> Make sure that appropriate health insurance has been taken out.<br /> On arrival make sure the whereabouts of the nearest doctor and<br /> hospital are known.<br /> The effects of travelling through different time zones may have<br /> to be compensated for.<br /> If the person suffers from travel sickness it may be appropriate to take<br /> travel sickness tablets; if sickness occurs then access to snacks to<br /> replace lost carbohydrate may be needed.<br /> 7. Diabetes is not caused by a microorganism. There is no way that a<br /> diabetic can pass on the condition by any of the obvious methods of<br /> transmission. Like many conditions, it has been suggested that<br /> diabetes may run in families but it cannot be ‘caught’ from anyone.<br /> 8. The technique ofgenetic engineeringhas enabled the human insulin<br /> gene to be transferred to more simple organisms. These organisms are<br /> then able to produce large quantities of pure human insulin in a<br /> relatively short time.<br /> (Some pupils may go into more detail about the procedures involved in<br /> genetic engineering.)<br /> Insulin keeps best in a fridge.<br /> <br /> pupil activity S4 A CASE HISTORY<br /> This is the story of a 39 year old woman who has been diagnosed as suffering from<br /> the more severe form of diabetes (early onset diabetes). It is quite unusual for<br /> someone to be diagnosed as having this more severe form of diabetes so late in life.<br /> "I had been experiencing 'strange' vision for a few weeks. I had very poor long<br /> sight but my short sight did not seem to be affected. My vision often<br /> appeared 'misty'. I could recognise large shapes, like trees, but couldn't see<br /> detail, such as the leaves on the tree. I thought I ought to see an optician<br /> about getting some glasses. I made an appointment. As it turned out, I didn't<br /> get to that appointment.<br /> I had other symptoms. I was very lethargic and felt very thirsty. I wasdrinking<br /> litres of orange juice at a time to try and quench my thirst. It was on a<br /> Thursday of one particular week that I began to feel really ill. I tried to make<br /> an appointment with the doctor but could not get one until the following<br /> Tuesday.<br /> The following day I could not even go to work. By the time Saturday arrived I<br /> was so desperate that I rang the doctor for an emergency appointment and<br /> went down to the surgery. Whilst sitting in the waiting room I remember<br /> feeling almost 'drunk' and 'completely out of it'.<br /> On hearing my symptoms, the doctor immediately suggested that I may be<br /> developing diabetes. I gave the doctor a sample of urine so that it could be<br /> tested for the presence of glucose. This test proved positive. The doctor<br /> then took a drop of blood from my finger to measure the amount of glucose in<br /> it. The normal level of glucose is between 4 - 7 mmol/dm<br /> 3<br /> . Mine was<br /> 26mmol/dm<br /> 3<br /> !! The doctor told me that this was a very good indication that I<br /> had a serious problem. He sent me immediately to hospital. I remained<br /> remarkably calm given the circumstances. I think I was just too ill to have any<br /> other sort of reaction!<br /> I arrived at the hospital at about 10.30am. I was weighed and had my height<br /> measured. They carried out two more tests. One tested for the presence of<br /> substances called ketones in the urine. These substances appear when the<br /> amount of insulin in the blood is low. This result was positive but it was not a<br /> major cause for concern at that stage. The other test is called the<br /> glycosylated haemoglobin test. This test is able to indicate the average<br /> glucose level in the blood for the previous few months. This resulted in a<br /> higher figure than normal. There was no doubt about it; I was definitely<br /> developing diabetes.<br /> These tests had taken quite a long time to perform. It was not until 2.30pm<br /> that the hospital decided they had enough information about me to enable<br /> them to estimate a correct amount of insulin to inject me with at that<br /> moment. They then taught me how to inject myself and how to measure my<br /> blood glucose levels. By 4.00pm that afternoon I was in a healthy enough<br /> state to be sent home.<br /> I returned the following morning and two days later for more help and<br /> information.<br /> A few days after my diagnosis, it hit me. I would be measuring my blood glucose<br /> levels and injecting insulin for the rest of my life. It seemed such a shock but<br /> now it is just part of my normal routing. It's not nice but it's manageable.<br /> <br /> A CASE HISTORY pupil activity S4<br /> Ms G has at least two very good factors in her favour. Firstly, she is not at all<br /> overweight. Secondly, she was already eating a suitable diet. The only changes she<br /> has had to make is that she avoids sweet, sugary foods like chocolate, cakes and<br /> puddings. She drinks low calorie (low kcal/kJ) or 'diet' versions of drinks. The only<br /> specialist diabetic product she has purchased is low sugar jam.<br /> For Ms G the greatest inconvenience is not the twice daily measuring of blood<br /> glucose levels. It isn't even the twice daily insulin injections. It is how nothing<br /> 'unexpected' can be allowed to happen with respect to food. There can be no<br /> skipped or missed meals; no surprise bars of chocolate; no unexpected delays at<br /> meal times, for example, in restaurants. It has also been surprising to find out that<br /> some people think they will be able 'catch' diabetes from her!<br /> Diabetics can and do lead full and active lives. More often than not their condition<br /> and their self discipline remain entirely unnoticed by the rest of us.<br /> You will have to do some research to answer the following questions.<br /> 1.At the beginning, Ms G described how her vision was being affected. Diabetics<br /> are allowed to have free and regular eye examinations. Find out why there is<br /> concern for a diabetic's eyes.<br /> 2.Ms G felt very thirsty and drank large amounts of orange juice. Why does diabetes<br /> make someone so thirsty? Why was drinking orange juice actually a mistake?<br /> 3.Diabetics can suffer hyperglycaemia and hypoglycaemia. What do these words<br /> mean? What symptoms are associated with these situations?<br /> 4.Diabetics are advised to wear some form of identification, such as a necklace or<br /> bracelet, explaining that they have insulin dependent diabetes. Why is this a<br /> sensible precaution?<br /> 5.Diabetics are advised to always carry with them some sugar or sweets. Why is this<br /> a sensible precaution?<br /> 6.What special considerations should a diabetic take when planning a holiday<br /> abroad?<br /> 7.How would you explain to someone that you cannot 'catch' diabetes from a<br /> diabetic?<br /> 8.Insulin was originally obtained by extracting it from the pancreas of cows. This led<br /> to objections from diabetics who were vegetarian. Also cow insulin is not the<br /> same as human insulin. Find out how modern technology has been able to<br /> produce sufficient quantities of 'human' insulin.