Chapter 6. Diabetic complications
Normal blood sugar control and the nature of diabetes 205
An overview of Type I and Type II diabetes 206
Infective complications in diabetes: the acute diabetic foot 242
Diabetes on the Acute Medical Unit: The General Approach
The illnesses to which diabetic individuals are susceptible will, in turn, have an adverse effect on diabetes control. Insulin requirements are increased in most acute medical conditions and diabetes control can become disrupted. Diabetic patients already on insulin may need careful adjustments: those not usually requiring insulin may need to have it introduced. Severe illness such as pneumonia or meningitis can even precipitate DKA. The level of short-term diabetes control may alter the longer-term outcomes in an acute illness. Recent evidence in acute myocardial infarction, for example, has shown that careful initial management of the blood sugars using an intensive insulin regimen can reduce the 1-year mortality rate by almost a third. There is increasing evidence that the same may be true in acute stroke: high blood sugars in the acute situation appear to have an important adverse influence on long-term stroke outcome. Clearly, the acute medical patient who is also diabetic can present some of the most taxing problems in terms of nursing and medical management.
The Acute Medical Unit nurse is presented with a dual challenge: to manage the primary acute medical problem and to ensure that the patient’s diabetes control does not have an adverse effect on the eventual outcome.
Diabetic emergencies, most notably ketoacidosis and hypoglycaemia, need immediate, expert management. Insulin-dependent diabetes can give rise to dramatic metabolic disturbances due to extreme changes in the blood sugar. The speed and accuracy of the initial assessment of the patient and the treatment in the first 2–3h of admission will have an important bearing on the prognosis. Box 6.1 lists the key points that should be checked in the acute admission of a diabetic patient.
Box 6.1
1. Is the patient hypoglycaemic?
2. Is this a diabetic emergency or an emergency in a patient with diabetes?
3. Confirm the timing of the last insulin/oral hypoglycaemic and the last meal
4. What is the usual regimen in this patient?
5. Critical nursing observations: GCS, pulse, blood pressure, temperature, respiratory rate, oxygen saturation, blood sugar, urinary ketones
6. Check vision
7. Skin: examine pressure points (heels, soles of the feet, ankles), remove dressings
8. Look for infection: cellulitis (legs and feet)/groins/vaginal discharge?
9. Examine the feet: numb/painful/infected/gangrenous?
10. Urgent venesection for biochemistry, etc.
Diabetic individuals are prone to infections: healing is often impaired and extensive soft tissue damage and loss can occur. The feet, in particular, are at risk from acute infection as a result of the combination of diabetic neurological and diabetic vascular damage. Such infections often present as emergencies with spreading infection, uncontrolled diabetes and, in many cases, a lower limb at risk of amputation.
Finally, it is important to take advantage of the opportunities that can arise on the Acute Medical Unit to influence long-term management. In particular, there is an important link between poor compliance and the risk of diabetic complications. A significant proportion of patients with diabetes only seek medical advice when major problems arise. For these patients, their acute admission provides an important chance to look for unrecognised complications and initiate a review of their overall diabetes management.
Aims of this chapter
• To provide an understanding of normal and abnormal blood sugar control
• To present an overview contrasting Type I and Type II diabetes
• To examine the acute medical conditions that are associated with diabetes
• To explain how to control the blood sugars in adverse medical situations
• To present the management of diabetic emergencies
• To look at the treatment of infection in the diabetic patient
• To identify opportunities on the Acute Medical Unit to influence longer-term management
Normal Blood Sugar Control and the Nature of Diabetes
The normal blood sugar level is kept within the range 4mmol/L to 8mmol/L by a balance between:
• the rate at which glucose is removed from the blood to be used by the muscles
• the rate at which glucose is manufactured by the liver and released into the blood
Insulin is released from the pancreas and reduces the blood sugar by:
• increasing glucose uptake and utilisation by the muscles
• reducing glucose formation and release by the liver
Normally, the pancreas senses the increase in blood sugar that occurs after food is eaten and secretes a carefully controlled amount of insulin. The insulin lowers the blood sugar and drives metabolism by pushing glucose into the cells, where it is used for energy.
If there is no insulin present, the body behaves as though it is in a state of acute starvation:
• the liver compensates by producing and releasing excessive glucose
• the muscles stop taking in and using glucose
• as a result, there is an acute increase in the blood glucose level
• fat is burnt as the alternative source of energy to produce fatty acids. These, in turn, form ketones, which are acids. Ketones appear in the blood and the urine
• the patient becomes acidotic (the blood pH falls)
Diabetes occurs in two situations:
• there is a complete failure of insulin production. This is the situation in Type I diabetes
• there is a reduction in insulin production and the tissues themselves are resistant to the actions of insulin. This is the situation in Type II diabetes
An Overview of Type I and Type II Diabetes
Type I (or ‘insulin-dependent’, IDDM) diabetes mellitus occurs when there is a progressive failure of insulin production.
Type II (or ‘non-insulin-dependent’, NIDDM) diabetes mellitus occurs when there is a combination of two factors:
• the tissues fail to react to insulin
• the rate of insulin production is reduced
There are fundamental differences between the two types of diabetes (→Table 6.1).
• Type I diabetes
— there is little or no naturally occurring insulin
— unless supplied with regular carbohydrate and insulin, the patient will become ketotic
• Type II diabetes
— there is a relative lack, but not a complete absence, of insulin
— blood sugars are elevated, but the patient is not usually at risk from DKA unless triggered by severe illness such as acute pancreatitis
| Clinical onset | Natural insulin | Risk of DKA | Obesity | Relative frequency | |
|---|---|---|---|---|---|
| Type I | Sudden | Nil | Yes | No | 20% |
| Type II | Slow | Low | Rare | 80% | 80% |
Type II diabetes
Type II diabetes is a partially inherited, age-related, ‘Western’ condition that has a strong association with obesity, a poor diet and physical inactivity. Insulin levels are moderately low (the number of pancreatic beta cells is reduced by around 20%). More importantly, the patient’s tissues are resistant to the action of insulin.
Recent Developments in the Treatment of Diabetes
Type I diabetes
There is increasing emphasis on tight blood sugar control to lessen the risks of long-term complications. In order to achieve this, there is a wide choice of insulin regimens and insulin injection devices. Many patients are now established on regimens with a basal background of single-dose, long-acting insulin that is fine-tuned by thrice-daily short-acting insulin regulated according to fingerprick blood sugar profiles. The importance of minimising postprandial increases in blood sugars has been realised and some patients use ultra-short-acting insulin (lispro/Novorapid®) with or even just after food to achieve this aim. New analogues such as insulin glargine and detemir are replacing isophane, the traditional basal insulin. Designed to be slowly released from the injection site, these insulins give a more physiological blood sugar profile and represent an important improvement in the management of Type I diabetes. Some patients are now fitted with an insulin pump – a Continuous Subcutaneous Insulin Infusion (CSII). This provides a basal infusion rate, which can be fine-tuned to alter throughout the day, and a bolus dose given by activating a button. In acute severe illness and DKA the pump should be disconnected and replaced with an intravenous insulin infusion. The dietary treatment of Type I diabetes remains based on an adequate calorie intake with complex carbohydrates, high fibre and a reduced fat intake.
Type II diabetes
Traditionally, management is based on dietary control with or without oral hypoglycaemics. The aims of dietary treatment in Type II diabetes are to reduce the energy intake, correct the blood lipids and reduce the patient’s weight. Drug treatment with oral hypoglycaemics acts by stimulating insulin secretion (e.g. glibenclamide and gliclazide), by re-sensitising the tissues to the action of insulin, or by directly reducing the release of glucose by the liver (metformin). In time, blood sugar control deteriorates – within 6 years of diagnosis, 25% of patients with Type II diabetes will require insulin. The effectiveness of combining once-daily insulin glargine or detemir with oral metformin has facilitated a much more active approach to blood sugar management, with the knowledge that this will improve the outlook.
Complications, in particular of vascular origin, are common in Type II diabetes. However, there have been major changes in our approach to their prevention. Up to 20% of new cases will have evidence of complications at the time of diagnosis and there is overwhelming evidence that the traditional ‘bad companions’ of diabetes have a major impact on the frequency with which they occur. Predictably, these are:
• hypertension
• hyperglycaemia
• hyperlipidaemia
• smoking
Large studies at the end of the 1990s have altered the perception of the importance of addressing these factors in patients with Type II diabetes. The evidence indicates that we must take every opportunity to re-enforce the need for good diabetic control and the need to reduce the other risk factors, notably hypertension and smoking. For example:
• Good long-term blood sugar control:
— reduces the risk of major diabetic eye disease by a quarter
— reduces the risk of early kidney damage by a third
• Lowering abnormally high blood pressure in these patients:
— reduces death from long-term complications by a third
— reduces the risk of strokes by a third
— reduces the risk of serious visual deterioration by a third
This represents a change of emphasis in management. The aim must be to keep the blood sugar and blood pressure in Type II diabetes as near normal as possible. The Acute Medical Unit often affords the first opportunity to address these issues, with both new and established diabetes.
Acute Medical Conditions Associated With Diabetes
AThe presence of widespread arterial damage in many diabetic patients makes them prone to a number of major acute medical problems. The cause of the damage is a combination of direct tissue toxicity from abnormally high sugar levels and the elevated blood lipids that are so common in diabetes. The effect of the damage depends on whether large (e.g. main coronary and cerebral arteries) or small (e.g. skin microcirculation and arteries within the kidney) vessels are predominantly affected (→Box 6.2). Unfortunately, in many of the older Type II diabetics there is damage throughout the arterial system, and these people are at risk from ischaemia affecting the coronary, cerebral and renal circulation.
Box 6.2
| Large vessel disease | Small vessel disease |
|---|---|
| Stroke Myocardial infarction Cardiac failure (coronary arteries) Amputation Sudden death (cardiac) |
Retinopathy (visual impairment) Renal failure (proteinuria/hypertension) Cardiac failure (heart microcirculation) Foot problems Sudden death (cardiac) |
Although there are no fundamental differences between the management of medical conditions in those with and without diabetes, diabetics as a rule fare less well than non-diabetics with the same disease. Thus diabetics with ischaemic heart disease have more widespread and more severe coronary artery disease and if they suffer infarct they have twice the mortality risk compared with non-diabetics. Complications are common, and often remain unrecognised by the patient. Thus a middle-aged patient with Type II diabetes may have heart muscle damage that only becomes apparent during other severe illnesses. Similarly, silent diabetic renal disease may lead to hypertension and its complications. It is therefore important that, when a patient with diabetes is admitted with a seemingly unrelated problem such as a urinary infection, the opportunity is taken to make a general assessment: for ischaemic heart disease, for hypertension and for kidney damage.
Tissues become damaged more easily and heal more slowly in diabetes. Immune function is reduced and organ damage is likely, especially where the blood supply is already compromised by diabetic vascular disease. Thus pneumonia is more likely to be complicated by empyema, renal infections may end in abscess formation and pressure sores may progress to osteomyelitis. Opportunistic infections may occur: examples include Candida infection of the skin creases and mucous membranes, pseudomonal infections of the ear and an unusual form of meningitis caused by the organism Listeria.
Diabetic renal disease
One-third of Type I and between one-quarter and one-half of Type II diabetic patients develop diabetic kidney disease (diabetic nephropathy). Diabetic nephropathy is the main cause of end-stage renal failure in the UK. Urinary protein loss is often the first indication of renal disease. Normally, we lose less than 30mg of albumin per 24h in the urine. An early sign that diabetes is affecting the kidneys is the presence of ‘micro’ albuminuria – a loss of 30–300mg per 24h – which can be detected using a specialised screening test. Once the protein loss exceeds 300mg per 24h, however, conventional testing of a random urine sample with Albustix® will be positive for protein. It is important to appreciate the significance of finding proteinuria in a diabetic patient on the Acute Medical Unit. It does much more than simply alert us to the possibility of a urinary infection.
• Proteinuria indicates probable renal involvement. (What are the patient’s urea and creatinine? Are there any previous records of kidney function in the notes?)
• Proteinuria goes hand-in-hand with cardiovascular complications and diabetic eye disease
• Proteinuria is strongly associated with hypertension
• Switching off the renin–angiotensin–aldosterone system (→p. 18) with ACE inhibitors (e.g. lisinopril) or angiotensin II receptor blockade (e.g. irbesartan) slows down the deterioration from microalbuminuria to advanced diabetic nephropathy.
If diabetic renal disease is discovered on the Acute Medical Unit for the first time, the patient must be referred on for specialist management so that the risk of further complications can be reduced by:
• careful blood pressure control
• treatment with ACE inhibitors and related drugs
• tight diabetic control
• correction of lipids
• advice on cessation of smoking
Diabetic neuropathy
Diabetic nerve damage is very common – it occurs in around one-third of patients with Type II diabetes. There are two types of diabetic neuropathy: peripheral neuropathy and autonomic neuropathy. Both are very relevant to the Acute Medical Unit nurse. Peripheral neuropathy gives problems in the feet: numbness, poor skin nutrition and impaired mobility. The patient has no warning of trauma to the feet, so minor abrasions can develop painlessly into infective ulceration. Nerve damage and muscle imbalance lead to foot deformity (claw toes) and pressure damage (calluses and ulcers) over abnormal bony prominences. Elsewhere in the body, nerve damage can lead to neuralgia with severe, recurrent and often undiagnosed pain in the thighs and abdomen.
Cardiovascular disease
Cardiovascular disease is a major problem in diabetes and shortens the life expectancy of the diabetic patient by between 5 and 10 years. Diabetics with ischaemic heart disease have more widespread and more severe coronary artery disease than the non-diabetic. The main manifestations of cardiovascular disease are angina, myocardial infarction and heart failure. Due to diabetic neuropathy and an increased pain threshold, angina can present late and myocardial infarcts can be painless. It is not unusual for an infarct to present as a sudden deterioration in diabetic control. The risk of a myocardial infarct is increased in diabetes – by a factor of two to three in Type II diabetes and by an order of a magnitude in Type I diabetes sufficient, for example, to cancel out the protective effect of their sex in a premenopausal diabetic female. There is also increased mortality risk both in hospital and during long-term follow-up. The heart muscle fares badly in these patients and the risk of re-infarction is high. The strong association between diabetes and hypertension also accelerates many of the cardiovascular complications.
Cerebrovascular disease
The vascular damage in diabetes affects both the larger cerebral vessels and the cerebral microcirculation. Patients with diabetes are at two to three times the normal risk of having a stroke. Should they suffer one, the mortality risk is higher and the functional outcome is worse than the equivalent stroke in a non-diabetic. Diabetic cerebrovascular disease presents with typical stroke-like symptoms due to thrombosis or hypertension-related cerebral haemorrhage. It is critically important, however, not to misdiagnose a neurological presentation of hypoglycaemia as a stroke. It should be assumed that any change in the consciousness level of a diabetic patient has a metabolic cause until proved otherwise.
Peripheral vascular disease
Diabetic peripheral vascular disease presents as an emergency with ischaemic problems in the limbs due either to acute arterial occlusion or to vascular complications in the feet: ulceration, infection and gangrene.
Blood Sugar Control in Adverse Medical Situations
Assessing control
What are ‘osmotic symptoms’?
Heavy glycosuria draws water into the urine by osmosis. Osmotic symptoms are therefore polyuria and thirst, and are a sign either of the onset of diabetes or of diabetes that is out of control. The strength of the osmotic diuresis can lead to dehydration but also to electrolyte loss, most notably of potassium and sodium.
Laboratory blood sugar versus fingerprick testing
Although the fingerprick blood sugar tests give values that are around 15% less than the laboratory blood sugars, they are an invaluable way to assess diabetic control in the acute, unstable situation. The main problem is the unreliability of the glucose stix at low blood sugar levels. Normally, the BM stix is used as the initial test in suspected hypoglycaemia, so that immediate action can be taken. Ideally, blood should be drawn simultaneously for checking in the laboratory.
Modern blood glucose meters
Glucose meters and glucose test strips have improved considerably in recent years. At one time they were difficult to use and prone to user error: too little blood on the strip would lead to under-reading; timing had to be to the second; and the technique for wiping blood off the strip was critical. Fortunately, the manufacturers have removed many of the user-dependent problems that led to their unreliability.
Meters such as the Ascensia Control® and the Optium Xceed™ are popular because they are reliable, easy to use and require very small amounts of blood – some do not need calibration (Control), and some also measure blood ketones (Xceed). It is critical that the meters are used properly. There must be a Standard Operating Procedure in place, a training programme and a Staff Training Record.
• The new, ‘virtually’ pain-free, adjustable finger-pricking devices should be in used. The lancet should be enclosed in the removable platform of the device, making both sharps injuries and inadvertent re-use impossibilities
Good practice in fingerprick testing is outlined in Box 6.3.
Box 6.3
• Have you re-read the instructions recently?
• Has your machine been calibrated?
• Is the finger warm, dry and clean? Are your hands dry and clean?
• Prick the side, not the pulp, of the finger tips
• Produce a large drop of blood by milking up from the finger base
• Don’t let the skin touch the test strip
• Apply the drop to the strip so that it covers the test area – do not smear it on
• Follow the instructions
• If you have to, wipe or blot off the blood as instructed
• Use the meter as instructed
• Do you audit your practice?
• How do your results compare with the laboratory sugars?
• Is your ward’s blood glucose monitoring subject to a Quality Control Programme?
What about urine testing?
Urine testing for sugar is unreliable for both the diagnosis and the accurate monitoring of diabetes and has been largely replaced by blood sugar measurement. Normally, glucose spills over from the blood into the urine once the blood sugar is above 11mmol/L, but the level can vary from as little as 7mmol/L to as much as 15mmol/L. While it may be justified to monitor the occasional patient using urine testing, this would only apply to perhaps the very elderly diabetic who has been admitted to hospital with an unrelated problem and in whom frequent fingerprick testing would be considered unkind and unnecessary. In such a patient it would be reasonable to assume that, if there is little or no glycosuria, then the diabetes is probably under reasonable control. On the Acute Medical Unit the urine test for sugar is most useful as an initial screening test. If heavy glycosuria is found, it is important to look for ketones (see later).
What about one high blood sugar on admission?
By its nature, the blood sugar in most medical admissions will be a random one rather than fasting. Acute illnesses raise the stress hormones glucagon, adrenaline (epinephrine) and cortisone. Their actions counteract those of insulin. This may lead to a temporary diabetic state or may unmask latent diabetes. This effect can be exacerbated by some of the drugs that are used on the Acute Medical Unit:
• corticosteroids: especially dexamethasone or high-dose methyl prednisolone
• diuretics
Similar considerations apply to Type I diabetics. In particular, single injections of insulin to ‘bring the sugar down’ are usually unhelpful, as they obscure the pattern of diabetic control and are no substitute for planned management of the diabetes, taking into account the medical condition and the patient’s nutritional needs.
In summary: considerations when planning short-term control include:
• Is there a risk of ketosis?
• Will the blood sugar levels directly influence the medical outcome?
• Are there osmotic symptoms (thirst and polyuria) or dehydration?
• What are the risks and consequences of hypoglycaemia?
What is the importance of urinary ketones?
There are three types of ketones (also known as ketone bodies):
• aceto-acetic acid
• acetone
• beta-hydroxybutyrate
Ketones are acidic substances that appear in the blood when there is excessive breakdown of the body’s fat stores. They are used by muscle as an important source of energy when glucose is not available, either because of fasting or because there is no insulin available to drive glucose into the muscle cells.
In fasting states and in dietary glucose restriction, the ketone production is insufficient to cause an acidosis, and there is only mild or moderate ketonuria. This is in contrast to the situation in severe insulin deficiency, in which there is a large rise in blood ketone levels that can lead to a dangerous acidosis (→Box 6.4).
Box 6.4
| • Starvation (extreme dieting, vomiting) | – | small to moderate amounts |
| • Strict dieting in obese Type II diabetes | – | small to moderate amounts |
| • Diabetic ketoacidosis | – | moderate to large amounts |
It is vital for nurses to appreciate the difference between starvation (or vomiting) ketosis and DKA. This is a particular issue in the anorexic or dieting Type II diabetic who shows moderate ketonuria: do you rush in with a DKA regimen, or can you reassure the patient and even congratulate them on sticking so rigidly to their diet? This depends on the clinical picture. In general, ketonuria is much more likely to indicate impending ketoacidosis in the thin Type I diabetic than in the obese patient whose diabetes is controlled with oral hypoglycaemics. Moreover, the patient with ketoacidosis is likely to have warning symptoms: thirst, hyperventilation and nausea. The action the nurse would take is also dependent on whether or not there is an acidosis. A diabetic patient with moderate ketonuria may look ‘too well’ for DKA; check for acidosis. A simple venous blood sample for plasma HCO3 level will reveal if there is cause for concern: if the bicarbonate level is low (less than 15mmol/L) there is acidosis, if it is normal, then both nurse and patient can be reassured.
Case Study 6.1 illustrates difficulties with blood sugar control in a Type II diabetic. The main problem was steroid-induced hyperglycaemia without ketosis. Metformin is a commonly prescribed first-line oral hypoglycaemic and tends to be used in obese Type II diabetic patients. It was a reasonable choice in this case, although precautions have to be taken when it is used. The main problems concern the risk of lactic acidosis – a life-threatening metabolic disorder. There are a number of situations in which metformin is contraindicated because of this risk, some of which are relevant to the Acute Medical Unit:
• after a myocardial infarction
• in renal failure
• in severe liver disease
• in patients who are shocked or critically ill
• in patients more than 80 years old
• in patients who are having i.v. contrast studies
Case Study 6.1
A 42-year-old overweight woman was admitted with a 3-week history of severe thirst and polyuria. Her blood sugar was 34mmol/L and there were no ketones in her urine. Her blood pressure was 160/115mmHg.
She had chronic asthma controlled on inhaled corticosteroids. For 8 weeks she had needed high doses of oral steroids 20–30mg daily to control her worsening symptoms.
Treatment with metformin did not drop her sugars sufficiently nor did it clear her osmotic symptoms. She was therefore treated with short-term insulin while her asthma was controlled and her oral steroids were withdrawn. She was referred to the respiratory unit for review of her asthma and control of her blood pressure.
A blood pressure of 160/115mmHg is unacceptable in a diabetic patient since any level of hypertension in a diabetic is associated with accelerated vascular and renal disease. Aggressive blood pressure control reduces the risks considerably and in this patient a target level of 140/80mmHg would be entirely reasonable. It is likely that, once oral steroids were withdrawn from this patient, both her hyperglycaemia and her hypertension will settle. Short-term insulin was indicated mainly because of the marked osmotic symptoms.
Case Study 6.2 brings out more difficulties associated with the use of metformin in the elderly diabetic. The main problem here relates to the interaction of an acute medical illness and the patient’s oral hypoglycaemic drugs, rather than hyperglycaemia itself. This patient presented a complex problem of acidosis but not ketosis and renal failure (high urea and creatinine). The blood sugar was normal. Metformin has caused a lactic acidosis and the two diuretics have combined to produce profound abnormalities in the sodium and potassium levels. Drug side-effects are common in elderly patients, and particular care has to be taken in the case of elderly diabetics, who are prone to complicated acute medical problems.
Case Study 6.2
An 80-year-old man with Type II diabetes presented with a 3-week history of vomiting, breathlessness and diminishing mobility. On admission he was breathless and shivering. His mental test score was 4/10 and his temperature 37.4°C.
Treatment had been metformin 500mg tds, spironolactone 100mg bd, frusemide 80mg od and gliclazide 160mg bd.
On admission test results were:
BP 150/62mmHg
WCC 21.8 × 109/L
potassium 8.6mmol/L, sodium 120mmol/L, urea 38.2mmol/L, creatinine 251μmol/L, sugar 6.4mmol/L, bicarbonate 5mmol/L, urine: no glucose and no ketones
Practical Management of Diabetes in Adverse Circumstances
Several situations are encountered on the Acute Medical Unit in which it would not be appropriate simply to continue with the patient’s usual diabetic regimen and in which the management of the diabetes becomes an important practical problem:
• acute medical conditions that destabilise the diabetes
• acute medical conditions in which hyperglycaemia should be avoided
• diabetic patients who are unable to eat and drink normally
Type I diabetics need insulin at all times, whether they are eating or not; the acutely ill medical patient who is also diabetic is at risk from rapidly changing sugar levels and the development of ketoacidosis. In these patients it is important to ensure tight control with as simple a regimen as possible. Whether Type II diabetics require the same intensive approach depends on the severity of the medical condition, but in many acute situations due priority has to be given to the diabetic control, in addition to treating the immediate medical problem.
GKI or Glucose and a Sliding Scale?
There are two techniques that are used to control diabetes in the sick and unstable patient: the careful use of i.v. insulin and glucose, either as a single infusion (bag) containing glucose, potassium and insulin (GKI), or as separate infusions of dextrose and a sliding scale of i.v. insulin (→Box 6.5).
Box 6.5
| GKI | Sliding scale |
|---|---|
| • Simple to use | • Requires volumetric pump and syringe driver |
| • Risk of water overload | • Risk of hypoglycaemia |
| • Insulin + glucose together | • Suitable for complex fluid regimens |
In some hospitals, the sliding scale technique is thought to have several disadvantages compared with the simpler GKI ‘single bag’ infusion:
• the infusions are complicated to administer
• the dependence on separate infusions of insulin and glucose increases the risk of inadvertent swings in the blood sugar
The opposing view is that the advent of sophisticated infusion and syringe pumps has simplified their administration and minimised the risk of error. There are also advantages in having the flexibility of two adjustable infusions, particularly in critical situations in which there is a need for complex fluid regimens.
The safest approach is to use the regimen that is most familiar to the unit and which has been shown to be trouble-free during its use. Whichever regimen is favoured, the key is the attention to detail in setting up and running the regimen, combined with an appropriate level of monitoring.
In these patients, the DKA regimen (see later) should be followed, only changing to a GKI infusion (or dextrose and a sliding scale of insulin) once the sugar value is less than 13mmol/L.
Glucose-potassium and insulin
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