Family doctor

Overview of diabetes

Diabetes is a condition characterised by an elevated blood glucose and it is usually caused by a problem with insufficient insulin being produced or an inability for the insulin to work properly. Insulin is a hormone produced by the pancreas and it helps move glucose (or sugar) from the blood into the body cells where it acts to provide energy for the body so that it can live and grow healthily. Too little insulin will result in high blood sugar levels and hence diabetes.

What kind of diabetes are there?

Type 1

About 10-15% of people with diabetes will have what is called Type 1 diabetes (insulin-dependent diabetes). These people have a significant deficiency in the production of insulin. What causes that is unclear, but it appears that there is a gene that predisposes the insulin-producing cells (B cells) in the pancreas to be destroyed by the immune system. Type 1 diabetes can occur at any age, not just in children. It can take many years to deplete the pancreas' stores of insulin and blood tests can test for antibodies that indicate that the destructive process is or has occurred. Because of a significant deficiency of insulin, almost all of the people with Type 1 diabetes will need to take insulin injections at or soon after the diagnosis.

Type 2

By contrast, Type 2 diabetes which makes up the bulk of people with diabetes, usually occurs in adults, although in countries where there is an increasing prevalence of obesity and diabetes, it is occurring in teenagers and even some children. It is characterised by both a deficiency in the production of insulin and also in the action of insulin (so called insulin resistance). It is more common in certain races and is becoming increasingly more prevalent in the world. It is estimated that the world-wide diabetes population will soon reach 200 million and it seems to be growing in parallel with an increasing prevalence of obesity and a sedentary lifestyle. One of the biggest explosions of diabetes may be occurring around the Pacific rim and Asia. The causes of Type 2 diabetes are not known but a number of gene defects have been noted. This type of diabetes runs more closely in families. Obesity occurs in 75-80% of patients and the disorder is often closely linked with high blood pressure and high lipid (cholesterol and triglyceride) levels and premature heart disease.

Gestational diabetes

Some people get their diabetes only in pregnancy (gestational diabetes). Gestational diabetes may occur in 2-4% of all pregnancies, higher in some races. While it usually disappears after the pregnancy, these people have a much higher risk of developing diabetes in later years.

People with diseases of the pancreas, e.g. haemachromatosis (an iron disorder) or alcohol damage can develop diabetes. Certain common drugs (especially Prednisone) can increase the chances of developing diabetes by increasing insulin resistance.

In summary, it appears that diabetes is a growing world-wide epidemic and the prevalence is increasing, particularly for Type 2 diabetes, but interestingly also for Type 1 diabetes.

Are there any risk factors for developing diabetes?

The major risk factors for Type 2 diabetes in particular are obesity, strong family history of diabetes, certain ethnicities, e.g. Hispanic, Maori, Polynesian, older age, people with high blood pressure or high cholesterol levels, and women who have had very large babies (greater than 4,000 grams). People in these categories should be screened for diabetes by their doctors. Many, if not most, pregnant women should be screened for diabetes during their pregnancy, especially women older than 25 years of age and with risk factors mentioned above.

Diagnosis - how do I know I've got it?

People who have a lot of risk factors for diabetes should obviously be screened. One of the interesting facts about diabetes is that it can often present with very non-specific symptoms or even no symptoms at all which makes the condition dangerous because it can then occur for years without detection causing complications before diagnosis is made.

There are however symptoms which should alert people to the diagnosis of diabetes. These include excessive urination and excessive thirst. If the blood glucose levels are very high, weight loss may ensue. Tiredness is a very common accompaniment of high blood glucose and the patient may be prone to symptoms of dehydration like cramps. Blurry vision is not uncommon which is usually a temporary phenomenon and not related at diagnosis to any permanent diabetic changes. Patients should avoid getting new spectacles at this early stage. Patients can sometimes have tingling in the feet or lower limbs at diagnosis which is sometimes quite uncomfortable and again is usually quite self-limiting. People are more prone to yeast infections, e.g. thrush, especially in the vagina and under the breasts, around the penis and sometimes in the mouth. Sometimes infections on the skin are slower to heal. Boils or carbuncles can occur with very elevated blood glucose levels.

Any of these symptoms should alert you or your doctor to the possible diagnosis of diabetes. Once the symptoms have occurred the diagnosis is usually very easily confirmed with a simple blood test. Current criteria dictate that the diagnosis of diabetes is made with classical symptoms and a blood glucose over 11 mmol/L or a fasting glucose over 7. The urine glucose is usually positive but can be misleading.

In general, patients with Type 1 diabetes will present, especially if they are younger, with more dramatic symptoms over a period of days to weeks. Classically, as people get older, the diagnosis comes on more gradually.

What are the consequences of uncontrolled high blood glucose levels?

The acute symptoms from uncontrolled diabetes have been mentioned above. In some patients with Type 1 diabetes, the blood glucose levels may become so high and the person become so dehydrated that they become semiconscious and lapse into what is called ketoacidosis. This is a condition where the lack of insulin has caused significant muscle and fat breakdown, the blood glucose levels are very high and the person's blood becomes acidic and there is an acetone smell to the breath from the high ketone levels (a breakdown product from fat). This condition is serious and needs to be treated with insulin pumped into the veins and a lot of rehydration in a hospital setting. It is caused by acute deficiency of insulin and sometimes occurs in the context of intercurrent illness, e.g. gastroenteritis when insulin is either omitted or insufficient for the situation. Sometimes an older person can get very high blood glucose levels and develop what is called non-ketotic coma and this is a condition that results from very high blood sugars but insufficient to cause ketones and it also requires urgent hospital admission for rehydration and stabilisation of blood glucose levels.

Other than these extreme situations, the major long-term consequences of high blood glucose relate to the chronic complications that affect particularly the blood vessels and the nerves. These occur after many years of uncontrolled blood sugar levels. Most of these can be prevented by good blood sugar control.

A. Eyes

Diabetes can affect the blood vessels at the back of the eyes causing leakage and what is called diabetic retinopathy. After 20 or more years of diabetes, most people will have some minor changes in their eyes, but there is little doubt that the better the blood sugar control over the years, the less the likelihood of anything serious occurring in the back of the eyes. Regular eye checks by an eye specialist will mean that potentially serious eye problems can be treated early. It is important to appreciate that most eye disease is silent and that people with diabetes will not necessarily get any symptoms and therefore will not know that they have diabetic eye disease. Therefore, it is important that regular eye checks are performed every 1 to 2 years. Laser therapy performed under local anaesthetic is a routine and safe form of treatment of serious vision-threatening eye changes. With regular surveillance blindness from diabetes should be an unusual phenomenon. Cataracts can also occur in diabetes, particularly as patients get older and these can be easily detected and treated with surgery.

B. Kidney disease

Diabetes is one of the leading causes of kidney failure in most western countries and again, the incidence of kidney disease relates directly to the level of diabetic control. It is also worsened by high blood pressure. Like the eye disease, it is important to achieve good glucose control and good blood pressure control to prevent this complication. Again, symptoms of kidney disease are rare, but fortunately a simple urine test performed each year testing for small amounts of albumin (microalbumin) can detect those with early kidney damage and those patients can be treated aggressively.

If patients do develop severe end-stage kidney disease it is usually after many years of uncontrolled diabetes and those patients nowadays are treated by various forms of dialysis or kidney transplantation. In some centres, combined kidney and pancreas transplantation is offered for patients with Type 1 diabetes and end-stage renal disease. At present, pancreas transplants are only done in most centres at the time of the kidney transplant. They do, however, offer the advantage of independence from insulin injections.

C. Diabetic nerve damage (Neuropathy)

Diabetes can damage the nerves, particularly those involving the feet, and to a lesser extent nerves in the hands. Often patients will complain of no particular symptoms but when formally tested will show a decrease in their perception of touch or temperature or vibration sense. Sometimes the nerve damage will lead to numbness that the patient will be able to appreciate. Sometimes the symptoms of nerve damage may lead to burning, discomfort or tingling or other uncomfortable sensations which can be particularly bothersome at night.

A variety of medications can help these symptoms. Sometimes these symptoms are self-limiting and occur during periods of poor control or even strangely during episodes of rapidly improved control of diabetes. Because the patient cannot always feel discomfort in the feet from diabetic nerve damage, injuries can occur without the person knowing and sometimes ulcers and blisters can occur which can then become easily infected. It is therefore vital that patients have regular examinations of their feet, not only by themselves, but also by foot specialists, e.g. podiatrists. As has been mentioned, it may take some time for this sort of complication to occur but some patients do have nerve damage at diagnosis suggesting that they have had their diabetes for longer than they think. The worst scenario from diabetic foot problems is infection sometimes leading to gangrene. Amputation occasionally occurs, but in good centres with early treatment, this should be an increasingly uncommon event.

Diabetic nerve damage can also affect other areas, including the bowel leading to constipation and occasionally diarrhoea or to the stomach where it leads to a feeling of fullness after meals in some people. Very unusually it can lead to a drop in blood pressure on standing causing dizziness. These symptoms tend to occur more in people who have had diabetes for many years with poor control.

One complication that largely results from diabetic nerve damage is impotence, also known as erectile dysfunction, or a difficulty in achieving an erection. The causes of this problem are multiple but certainly nerve damage after a number of years is one of the causes. Again, a number of treatments are available now to help this, including Viagra.

D. Large vessel damage

Diabetes not only damages nerves and the small vessels involving the eyes and the kidneys, but also the larger vessels and hence people with diabetes that is not well controlled are more likely to have heart attacks and strokes and circulation problems in the legs than people without diabetes. This is partly related to the fact that they have high blood sugar levels and also because people with diabetes are more likely to have other risk factors for blood vessel damage including high blood pressure and high lipid levels (high cholesterol).

The general attitude to diabetes from your health professionals is one of aggressive management of not only blood sugar levels but also blood pressure and blood cholesterol levels. Many patients will also be on small doses of aspirin if they have one or two of these risk factors to help the circulation.

TYPE 1 DIABETES MANAGEMENT

Diabetes, no matter what the type, is a balancing act. It requires a careful balance of food, exercise and insulin or tablets to keep the blood sugar as close to normal as possible without causing it to go too low. The normal blood sugar aimed for is between 4 and 7 mmol/L.

Food Plan. The essential components of a food plan for diabetes include a limitation of sugary foods, e.g. sugar, honey, jams, chocolate, sweet biscuits, soft drinks and many fruit juices. Ideally the food plan should be relatively low in fatty foods. The food plan is essentially that recommended for the healthy population and is one that is often endorsed by the Heart Foundations of countries as well. Patients requiring insulin require 3 meals a day and will often need a snack, particularly at morning tea and at supper to prevent low sugar levels. New types of insulin recently developed may mean that "in between" snacks are required less often. In general, people with Type 1 or Type 2 diabetes do not need special diet, foods or supplements. If there is sufficient fruit and vegetables, there is no necessity to take extra vitamins or mineral supplements. Alcohol should be discussed with the patient's own health professional but generally it is safe to take in small quantities, especially in relationship to food. A dietitian is often available in most centres to provide expert advice on food plans and everybody with diabetes should see a dietitian to individualise their eating plan.

Exercise. Patients with Type 1 diabetes are encouraged to exercise. It is important to realise that prolonged exercise can lower the blood sugar levels and sometimes extra food is required and a reduction in insulin. In general exercise promotes a lower blood pressure, lower blood lipid levels, and may lead to more even blood sugar control and lower insulin requirements in some people.

Insulin. Patients with Type 1 diabetes require insulin to maintain their blood sugar levels within the normal range. There are a number of insulins available and people require usually somewhere between 2 and 4 injections per day. Insulin is given via a very tiny needle attached to either a small disposable syringe or "pen" which can be carried around easily. Insulin is best injected just under the skin in the abdomen region or sometimes the thigh. Instruction on its use is usually given by a diabetes nurse. The diabetes specialist will sort out what sort of dose is required and how frequently injections are needed.

Hypoglycaemia. The most important side effect from insulin is "hypoglycaemia" or a low blood sugar. Hypoglycaemia occurs under several circumstances:

• when a meal or snack is missed, particularly during more active periods
• when exercise is more active or prolonged than normal
• when the insulin dose is excessive for the circumstance

If the cause for the low blood sugar cannot be found it is important to contact the doctor or nurse for advice. The symptoms of a low blood sugar include: trembling hands, weakness, blurred vision, a pins-and-needles-type feeling in the lips or tongue, and sometimes a thumping heart and sweating. Often there is a feeling of mild confusion or irritability or anxiety and a lack of concentration is common. The patient will often look pale and the skin will be sweaty so often others may recognise it before the patient does. The blood sugar will be below 4 mmol/L and the treatment is to take a glucose tablet or sweet drink. The glucose is conveniently provided in special tablets. If this is not available, a tablespoon of jam or honey or a glass of ordinary soft drink or unsweetened fruit juice may work almost as well. The treatment is repeated if the patient is not feeling better within 5-10 minutes and once recovered, they should usually follow up this emergency treatment with a meal or at least a snack, e.g. a slice of bread or a sandwich or a glass of milk. Family and friends should know how to treat "hypos" and if patients are on insulin they should always carry some identification to say that they have diabetes and are on insulin.

Testing. Blood sugar testing is required to decide how much insulin to give and how to adjust insulin for certain circumstances, e.g. exercise or different size meals. It is crucially important to test if there is doubt about whether the blood sugar is low or not. Testing involves a small finger prick and a small pocketsize portable machine will measure the blood sugar usually within 30 seconds. It is important to record the blood sugar tests so that the patient and their doctor or nurse will be able to make appropriate treatment changes. Testing may need to be done up to 4 times per day in some people and once blood sugar levels become more stable then it may be possible to do tests less frequently.

TYPE 2 DIABETES MANAGEMENT PRINCIPLES

Food. While it is clear that Type 2 diabetes is not caused by obesity there is a strong link between the two, and weight loss becomes the key ingredient of the management. It is of interest that only a small amount of weight loss is required to normalise blood sugar levels. There is a clear need for a healthy eating plan with again a limitation on sugary foods and particularly for those who are overweight, a requirement to lower the fat content of food. A healthy food plan should be balanced and a dietitian will give you these as required. Often, however, it will be found that the "diabetic diet" is really no different from a healthy food plan which is recommended for most people today.

Exercise. A regular exercise programme will help several aspects of management of patients with diabetes. Regular exercise, at least 3 times a week for 20-30 minutes, may help sensitise the body to insulin as well as encourage weight loss, blood pressure and blood fat levels. It should be embarked on slowly and an individual programme (green prescription) is wise and should be discussed with the doctor. Sometimes too much exercise is not a good idea if the patient has a heart condition or joint problems and therefore the type of exercise needs to be discussed with their own doctor. The most important thing about exercise is that it be enjoyable and that it be maintained and the principle of "any exercise is better than none" is a good one.

Diabetic tablets. When blood sugar levels cannot be normalised, then diabetic tablets are required. The results of several studies, including the large UK PDS Study, has confirmed the importance of blood sugar control as well as the importance of good blood pressure control in people with Type 2 diabetes (as well as Type 1 diabetes). There are a variety of tablets which work in different ways. For instance, there are tablets that primarily work on the problem of insulin resistance. (Drugs like metformin and troglitazone help sensitise the body to insulin and are therefore useful in patients with Type 2 diabetes where insulin resistance is a problem). Because there is also a problem with insulin suppression, there are drugs (sulphonylureas) which help stimulate the pancreas to produce more insulin. Drugs like Glipizide, Gliclazide, Glibenclamide are examples of this type of drug. There are also drugs that stop the absorption of carbohydrates. These so-called starch-blocking drugs, e.g. Acarbose, can also help lower blood sugar levels.

The type of drug used will be dictated by the doctor and any potential side effects should be explained. The main side effect from the Sulphonylurea-type medications is hypoglycaemia. Low blood sugar reactions tend to occur when patients miss meals or snacks or are given an inappropriate dose of the drug. Similarly, excessive exercise can make you prone to hypoglycaemia. The risk is greater for the elderly and for those with impaired kidney or liver function. Metformin is a drug which very rarely will cause hypoglycaemia. Its main side effects relate to side effects like nausea or diarrhoea. It should be taken with or after food and if, with dose reduction, side effects continue, it should probably be discontinued. Acarbose not uncommonly will cause some flatulence which usually improves with time, but may not.

Insulin. Patients with Type 2 diabetes may still not be well controlled after a good food plan and exercise programme and appropriate medication. In this situation insulin may be required. It may be given as a single injection at night with the tablets continued or may be transferred to a 2 or 3 injection insulin programme without tablets. In general, diabetes is a progressive disorder and over time a more intensive medication programme is usually needed.

Monitoring the blood sugar levels is important in Type 2 diabetes but will depend on the type and number of medications the patient is on. Again, record keeping is important.

Other tests to monitor progress

In Type 1 and Type 2 diabetes, laboratory tests are required to monitor your progress. The haemoglobin A1C is the best measure for assessing the level of diabetic control. Depending on the method used, a level of 7% is aimed for but levels under 8% are generally considered to be reasonable. This test may need to be done up to 3-monthly in some people. Other tests that need to be performed include:

• urine test to monitor kidney function
• blood fat levels (cholesterol & triglyceride levels)
• tests for kidney function

Regular blood pressure assessment and appropriate treatment (usually to <140/85) and examination of the feet is needed by the health team. An eye specialist should review eyes every 1 to 2 years depending on the findings. It is helpful if patients carry records of their results themselves to help discussion with their doctors.

Diabetes is a very common disorder. It can be controlled and it is important to appreciate that with attention to detail and careful monitoring of blood sugar, blood pressure and blood fat levels, most of the complications from diabetes can now be prevented.