Abc do diabetes

Abc do diabetes

(Parte 1 de 19)

Peter J Watkins

DIABETES Fifth edition

ABC OF DIABETES Fifth Edition

ABC OF DIABETES Fifth Edition

PETER J WATKINS Honorary Consultant Physician, King’s Diabetes Centre, King’s College Hospital, London

©BMJ Publishing Group Ltd 1983, 1988, 1993, 1998, 2003

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording and/or otherwise, without the prior written permission of the publishers.

First edition 1983 Second edition 1988 Third edition 1993 Fourth edition 1998 Fifth edition 2003 by BMJ Publishing Group Ltd, BMA House, Tavistock Square, London WC1H 9JR w.bmjbooks.com

British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library

ISBN 0-7279-16939

Typeset by Newgen Imaging Systems (P) Ltd, Chennai, India. Printed and bound in Spain by Graphy Cems, Navarra.

The cover image shows molecular graphics of insulin hexamer with permission of JC Revy/Science Photo Library

Contents

Acknowledgments vi Introduction vii

1What is diabetes?1 2Clinical presentation: why is diabetes so often missed?7 3Aims of treatment: a healthy lifestyle10 4Treatment of Type 2 diabetes mellitus14 5 Insulin treatment 19 6Blood glucose monitoring: optimising diabetic control25 7The unstable Type 1 diabetic patient30 8 Hypoglycaemia 32 9Diabetic ketoacidosis and management of diabetes during surgery37 10Diabetic complications: cause and prevention42 1 Retinopathy 47 12 Peripheral neuropathies 51 13 Autonomic neuropathy 53 14Mononeuropathies and acute painful neuropathies57 15The diabetic foot59 16 Diabetic nephropathy 65 17Cardiovascular disease, hypertension, lipids, and myocardial infarction72 18 Pregnancy 7 19Organisation of diabetic care: primary-secondary care interface82 20 Practical problems 8

Appendix 191 Further information 92 Index 95

Any ideas or inspiration which these pages may contain have inevitably been learnt or borrowed from others. I am indebted to the late Professor JM Malins and Dr MG FitzGerald, through whose enthusiasm I was first introduced to diabetes, and to the late Dr David Pyke through whose energy this interest has been fostered over many years. Close collaboration with colleagues at King’s both past and present has made possible many of the joint ventures described here, and I am grateful to them all. Our registrars and research fellows and above all our patients have been a constant source of inspiration.

I am particularly grateful to the many colleagues who have assisted me with the preparation of this book, especially Professor Stephanie Amiel (RD Lawrence Professor of Diabetic Medicine), Dr Michael Edmonds and Dr Stephen Thomas (consultant physicians), Dr Tyrrell Evans (general practitioner), Dr Phin Kon (renal physician), Dr William Marshall (Reader in Clinical Biochemistry), Dr Joanna Raeburn (associate specialist), Ms Helen Reid (Diabetes Specialist Nurse), and Mrs Eileen Turner (Consultant Nurse Specialist). Dr Simon Page (consultant physician in Nottingham) has helped me considerably by his many valuable comments in reading the manuscript. My wife Mrs Val Watkins has throughout provided me with invaluable support and encouragement.

Consultant physicians to the Diabetes Centre at King’s from 1938 (from left to right) Dr Wilfred Oakley (1905-1998); Dr David Pyke (1921-2001) and Dr Peter Watkins

Acknowledgments

vii

Introduction

Advances in clinical science over a single professional lifetime during the second half of the 20th century have led to improvements in understanding the causes and complications of diabetes, together with alleviation of suffering to an extraordinary degree, unimaginable even 25 years ago. Many of the clinical improvements have been initiated at innovative centres across the United Kingdom.

In the 1960s and 1970s physicians had to stand by helplessly watching their patients overwhelmed by complications of the disease. Prevention of blindness by photocoagulation and renal support treatment for those in renal failure became possible in the 1970s, while development of specialist foot clinics during the 1980s succeeded in halving the amputation rate. The sad outcome for pregnancies even 20 years after the discovery of insulin when the fetal mortality rate was more than 25%, has been transformed so that now more than 95% of these pregnancies succeed. And now, the landmark Diabetes Control and Complications Trial (DCCT) of Type 1 diabetes in the United States, and more recently the astonishing achievement of the late Professor Robert Turner in completing the United Kingdom Perspective Diabetes Survey (UKPDS) of Type 2 diabetes have demonstrated how to reduce the incidence and progression of diabetic complications by good treatment.

Yet there is still more. The present technology of managing diabetes was undreamt of until the last quarter of the 20th century. The introduction of home blood glucose monitoring with new non-invasive technologies now in sight, has made possible the achievement of “tight control”, while at the same time advances in understanding and reversing diminished awareness of hypoglycaemia are reducing its hazards. The invention of insulin pens and more recently the development of insulin pumps has contributed in great measure to improving the quality of life of those with the burden of lifelong diabetes. Furthermore after the British discoveries of the chemical (Frederick Sanger, 1955) and physical structure (Dorothy Hodgkin, 1969) of insulin followed by the revolution in molecular science, man-made insulin analogues have been introduced, giving further advantages in achieving good blood glucose control while minimising hypoglycaemia.

The initially controversial “invention” of the diabetes specialist nurse by Dr Joan Walker in Leicester in the 1950s is arguably one of the most important advances in health care, not only for those with diabetes but across the whole of medicine. The tremendous benefits in the delivery of care especially to those with diabetes and other chronic diseases have been accompanied by recognition of community needs and improvements in crossing the primary/secondary care interface. It is now to be hoped that improvements in information technology, more sophisticated audit, and provision of a national eye screening programme may emerge from the National Service Framework of 2002/2003.

Rapid clinical advances of this magnitude require substantial support. Diabetes UK, founded as the Diabetic Association by Dr RD Lawrence and his patient HG Wells in 1934 (later the British Diabetic Association), has uniquely supported both patients and their needs as well as clinical and scientific research. More recently the Juvenile Diabetes Foundation has made substantial contributions. Furthermore the pharmaceutical industry has been both innovative in its own laboratories as well as supportive of both patients and clinicians.

It gives particular pleasure to reproduce some parts of the personal account by Mrs B-J (with her permission) of her own diabetes over the last 70 years of attendances at King’s College Hospital. She describes vividly aspects of treatment and some of the problems faced by people with diabetes, and one can see clearly how many improvements there have been during her lifetime. Her account should give tremendous encouragement to those now starting on their own life with diabetes.

The ABC is intended as a strictly practical guide to the management of diabetes and its complications and is directed to all those doctors, nurses, and health professionals, other than established specialists, who see diabetic patients, and medical students should find some value in its pages. Many of the innovations of the end of the 20th century are described in this fifth edition of the ABC in the hope that it will help in the delivery of the very best standards of care to those who need it in the 21st century.

RD Lawrence 1892-1968. Founder of the diabetic clinic at King’s in the 1920s, founder of the British Diabetic Association in 1934

Diabetes once diagnosed is for life. The perseverance and self discipline needed over a lifetime can often tax even the most robust of people to the limit. Those caring for them also require perseverance and an understanding of humanity combined with a cautious optimism, to guide those with diabetes through the peaks and troughs of their lives.

Definition

Diabetes occurs either because of a lack of insulin or because of the presence of factors that oppose the action of insulin. The result of insufficient action of insulin is an increase in blood glucose concentration (hyperglycaemia). Many other metabolic abnormalities occur, notably an increase in ketone bodies in the blood when there is a severe lack of insulin.

Diagnosis

The diagnosis of diabetes must always be established by a blood glucose measurement made in an accredited laboratory.

Glucose tolerance test The glucose tolerance test is not normally needed in routine clinical practice, and then only if uncertainty exists in younger patients, or to establish an exact diagnosis in pregnancy. For reliable results, glucose tolerance tests should be performed in the morning after an overnight fast, with the patient sitting quietly and not smoking; it is also important that the patient should have normal meals for the previous three days and should not have been dieting. False results may also occur if the patient has been ill recently or has had prolonged bed rest. Blood glucose concentrations are measured fasting and then one and two hours after a drink of 75g of glucose in 250-350ml water (in children 1·75g/kg to a maximum of 75g), preferably flavoured, for example, with pure lemon juice. Urine tests should be performed before the glucose drink and at one and two hours. Interpretation of blood glucose values according to WHO criteria is shown in the table.

Gestational diabetes This term embraces the criteria for both diabetes and impaired glucose tolerance when discovered during pregnancy (see page80).

Glucose tolerance tests may also show: Renal glycosuria—this occurs when there is glycosuria but normal blood glucose concentrations; this is a benign condition, only rarely indicating unusual forms of renal disease. It is worth issuing these patients with a certificate to prevent them from being subjected to repeated glucose tolerance tests at every medical examination.

Steeple or lag curve—this is described when fasting and two hour concentrations are normal, but those between are high, causing glycosuria; this is also a benign condition, which most commonly occurs after gastrectomy but may occur in healthy people.

Impaired glucose tolerance This is defined in the table. Patients are managed at the discretion of the physician. In general, no treatment is given to

1What is diabetes?

Ebers papyrus: early clinical description of diabetes (Egyptian, 1500BC)

WHO criteria for the diagnosis of diabetes

1Symptoms of diabetes plus casual venous plasmaglucose 11·1mmol/l. Casual is defined as any time of day without regard to time since last meal. The classic symptoms of diabetes include polyuria, polydipsia, and unexplained weight loss 2Fasting plasmaglucose 7·0mmol/l or whole blood 6·1mmol/l. Fasting is defined as no calorie intake for at least 8 hours 32 hour plasmaglucose 11·1mmol/l during oral glucose tolerance test using 75g glucose load

In the absence of symptoms, these criteria should be confirmed by repeat testing on a different day. If the fasting or random values are not diagnostic, the 2 hour value post-glucose load should be used

Note: Fasting plasma glucose 6·1mmol/l—normal Fasting plasma glucose 6·1 and 7·0mmol/l—impaired fasting blood glucose Fasting plasma glucose 7·0mmol/l—provisional diagnosis of diabetes; the diagnosis must be confirmed (see above)

Adapted from Diabetes Care1997;20:1183-1195

Glucose tolerance test

Glucose concentration (mmol/l)

Venous Capillary Venous whole bloodwhole bloodplasma

(Parte 1 de 19)

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