Abc do diabetes

Abc do diabetes

(Parte 4 de 19)

Prevention of Type 2 diabetes

Lifestyle changes in those prone to Type 2 diabetes can effectively delay the onset of this disease. Several studies in different countries have demonstrated the feasibility of achieving this by a programme of weight reduction, improved diet (less fat, less saturated fat, and more dietary fibre) and increased physical activity. Recent investigations show that the development of diabetes can be approximately halved if these lifestyle changes are maintained over four years.

Diabetic complications

Patients with long-standing diabetes, both Type 1 and Type 2, may develop complications affecting the eyes, kidneys or nerves (microvascular complications) or major arteries. The major arteries are affected in people with diabetes, causing a substantial increase both in coronary artery disease and strokes as well as peripheral vascular disease. The greatest risk of large vessel disease occurs in those diabetic patients who develop proteinuria or microalbuminuria, which is associated with widespread vascular damage. The distribution of arterial narrowing tends to be more distal than in non-diabetic people, whether in coronary arteries or in the peripheral arteries affecting feet and legs. Medial arterial calcification (Monckeberg’s sclerosis) is also substantially increased in patients with neuropathy and in those with renal impairment. The functional effects of vascular calcification are uncertain.

ABC of Diabetes

Year

Cumulative incidence of diabetes (%)

Placebo Metformin Lifestyle

Cumulative incidence of diabetes according to the Diabetes Prevention Programme Research Group. The diagnosis of diabetes was based on the criteria of the American Diabetes Association. The incidence of diabetes differed significantly among the three groups (P 0.001 for each comparison), showing that lifestyle interventions are particularly effective in diminishing the development of Type 2 diabetes

The illustration of an islet cell is reproduced from Gepts WInsulin: islet pathology, islet function, insulin treatment, Loft R, ed. Nordisk Insulinlaboratorium. The bar chart showing relative risk of type 2 diabetes according to body mass index in US women uses data from Colditz GA, et al. Ann Intern Med1995;122:461-86. The figure showing a family with dominantly inherited Type 2 diabetes is adapted from Fajans S, et al. History, genetics and pathogenesis of HNF-4a/MODY1: a 40-year prospective study of the RW pedigree. In Frontiers in Diabetes. Basel: Karger, 2000. The age of onset chart is adapted from Diabetes in Epidemiological perspective, Mann JI, et al, eds. Churchill Livingstone, 1983. The bar chart showing number of people over 20 years estimated to have Type 2 diabetes in developed and developing countries is adapted from King H, Rogtic G. Global status of diabetes and recommendations for international action. International Diabetes Monitor.Copenhagen: IFDOR (Novo Nordisk). The seasonal incidence is adapted from Bloom A, Ireland J, Watkins PJ. A Colour Atlas of Diabetes. Wolfe Publishing Ltd, 1992. The estimated prevalence of diabetes in countries in 2000 is adapted from the executive summary of Diabetes Atlas 2000, with permission from the International Diabetes Federation. The figure showing cumulative incidence of diabetes according to the Diabetes Prevention Program Research Group is adapted from Diabetes Prevention Program Research Group. New Engl J Med 2002;346:393-403. Copyright Massachusetts Medical Society. All rights reserved.

Thirst, tiredness, pruritus vulvae or balanitis, polyuria, and weight loss are the familiar symptoms of diabetes. Why then is the diagnosis so often missed? Of 15 new patients with diabetes presenting in our diabetic ward for the first time with ketoacidosis, 14 had had no tests for diabetes after a total of 41 visits to their doctors. Almost all these serious cases of ketoacidosis could have been prevented.

Patients do not, of course, always describe their symptoms in the clearest possible terms, or else their complaints may occur only as an indirect consequence of the more common features. Many patients describe dry mouth rather than thirst, and patients have been investigated for dysphagia when dehydration was the cause. Polyuria is often treated blindly with antibiotics; it may cause enuresis in young people and incontinence in elderly people and the true diagnosis is often overlooked. Complex urological investigations and even circumcision are sometimes performed before diabetes is considered.

Confusion in diagnosis

Some diabetic patients present chiefly with weight loss, but even then the diagnosis is sometimes missed, and I have seen two teenagers referred for psychiatric management of anorexia nervosa before admission with ketoacidosis. Perhaps weakness, tiredness, and lethargy, which may be the dominant symptoms, are the most commonly misinterpreted; “tonics” and iron are sometimes given as the symptoms worsen.

Deteriorating vision is not uncommon as a presentation, due either to change of refraction causing myopia (mainly in Type 1 diabetes) or to the early development of retinopathy (mainly in Type 2 diabetes). Foot ulceration or sepsis in older patients brings them to accident and emergency departments and is nearly always due to diabetes. Occasionally painful neuropathy is the presenting symptom, causing extreme pain in the feet, thighs, or trunk.

Glycosuria itself is responsible for the monilial overgrowth which causes pruritus vulvae or balanitis; some older men are first aware of diabetes when they notice white spots on their trousers. In hot climates drops of sugary urine attract an interested population of ants, and at least one patient now attending the clinic at King’s College Hospital presented in this way before he came to England.

Patterns of presentation

Symptoms are similar in the two types of diabetes (Type 1 and Type 2), but they vary in their intensity. The presentation is most typical and the symptoms develop most rapidly in patients with Type 1 diabetes; they usually develop over some weeks, but the duration may be a few days to a few months. There is usually considerable weight loss and exhaustion. If the diagnosis is missed, diabetic ketoacidosis occurs. Type 1 diabetes occurs under 40 years of age in approximately 70% of cases but can occur at any age, and even in older people.

2Clinical presentation: why is diabetes so often missed?

Before insulinFour months after insulin

Before insulinAfter insulin Insulin dependent diabetes, 1922

Time since diagnosis (years)

Retinopathy (%)

Clinical diagnosis

Presence of any retinopathy according to years since clinical diagnosis of Type 2 diabetes among patients in Southern Wisconsin ( ) and rural Western Australia ( ). Solid lines represent data fitted by weighted regression; lines are extrapolated to indicate the time at which onset of observable retinopathy is estimated to have occurred, demonstrating that diabetes was likely to have been present for several years before the clinical diagnosis was made

ABC of Diabetes

Symptoms in patients with Type 2 diabetes are similar but tend to be insidious in their onset; sometimes these patients deny any symptoms, although they often admit to feeling more energetic after treatment has been started. These patients are usually middle aged or elderly, but increasingly children, especially those of ethnic minorities, or those who are inert and overweight, are developing Type 2 diabetes. Microvascular and macrovascular complications are frequently already present when Type 2 diabetes is diagnosed. Type 2 diabetes is commonly detected at routine medical examinations or on admission to hospital with another illness.

Identifying patients in need of insulin

Patients in need of treatment with insulin must be identified early. This is done by judging the patient’s clinical features; blood glucose concentrations alone offer a relatively poor guide, although most patients with a blood glucose concentration greater than 25mmol/l are likely to need insulin. Features suggesting need for insulin are:

•a rapid development of symptoms

•substantial weight loss—patients are usually thin and demonstrate a dry tongue or more severe dehydration

• weakness •the presence of ketonuria.

If their condition worsens, vomiting can occur and they rapidly become ketoacidotic; these patients are drowsy, dehydrated, overbreathing, and their breath smells of acetone (although many people are unable to detect this smell). The following groups of patients are likely to need insulin:

•almost all children and most of those under 30-40 years of age

•women who present during pregnancy •diabetic patients whose tablet treatment has failed

•all patients who have undergone pancreatectomy.

If there is any doubt give insulin. It can never be wrong to do so, and if the decision was mistaken it can easily be reversed.

Opportunistic screening

The diagnosis of diabetes should no longer be missed. New patients attending their doctor, whether the family doctor, at a hospital outpatient clinic or accident and emergency department, should have a blood glucose measurement as a matter of routine, especially if their symptoms are unexplained. Only a few diabetic patients are wholly without symptoms and their diabetes should be detected by screening at any medical examination. Opportunistic screening for diabetes in this way is a duty.

Presenting symptoms (%) in 547 consecutive cases of diabetes seen by Professor John Malins

Symptoms

Pruritus Age Males Females Total None Thirst Wasting Fatigue vulvae Sepsis Visual Other

*Cases of balanitis in males

Type 2 diabetes—presentations

• Infections 16% (for example, candida)

• Diabetic complications 2%

Identifying patients in need of insulin

Symptoms Age •Rapid onset•Any, more likely under 30 years

•Substantial weight loss

Signs •Usually thin

(Parte 4 de 19)

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