Perioperative management of the patient with diabetes requiring emergency surgery

Abstract

Key points•About 100 000 emergency surgical procedures are performed per annum in the UK on patients with diabetes. Diabetes is a recognized factor for a patient to become the higher risk surgical patient.•The emergency surgical patient with diabetes requires meticulous initial assessment and planning to allow the diabetes, the diabetes medication and any other associated comorbidity to be optimally managed. A number of modifiable risk-factors have been identified, and by optimizing these modifiable risk factors, outcomes can be improved.•For the majority of patients, the variable rate i.v. insulin infusion (VRIII) is required to control the diabetes and maintain optimal glycaemic control of 6–10 mmol litre−1. When and where possible, the patient with diabetes requiring expedited surgery should be managed by simple manipulation of their diabetes medication.•The goal of the intraoperative care/anaesthetic technique is to promote early resumption of eating and drinking and return to normal medication, whilst simultaneously preventing morbidity from glycaemic variability, acute kidney injury (AKI), fluid, and electrolyte imbalance amongst other complications. •About 100 000 emergency surgical procedures are performed per annum in the UK on patients with diabetes. Diabetes is a recognized factor for a patient to become the higher risk surgical patient.•The emergency surgical patient with diabetes requires meticulous initial assessment and planning to allow the diabetes, the diabetes medication and any other associated comorbidity to be optimally managed. A number of modifiable risk-factors have been identified, and by optimizing these modifiable risk factors, outcomes can be improved.•For the majority of patients, the variable rate i.v. insulin infusion (VRIII) is required to control the diabetes and maintain optimal glycaemic control of 6–10 mmol litre−1. When and where possible, the patient with diabetes requiring expedited surgery should be managed by simple manipulation of their diabetes medication.•The goal of the intraoperative care/anaesthetic technique is to promote early resumption of eating and drinking and return to normal medication, whilst simultaneously preventing morbidity from glycaemic variability, acute kidney injury (AKI), fluid, and electrolyte imbalance amongst other complications. Diabetes is the most common metabolic disorder, affecting at least 6–7% of people in the UK. The most recent data from the National Diabetes Inpatient Audit showed that in 2013 the prevalence of diabetes in the UK in-patient hospital population ranged from 10 to 35%.1Health and Social Care Information CentreNational Diabetes Inpatient Audit (NaDIA), open data—2013. 2014http://www.hscic.gov.uk/catalogue/PUB14358Google Scholar Diabetes-related co-morbidities increase the need for surgical and other operative procedures, thus at least 10% of patients undergoing emergency surgery have diabetes. Diabetes leads to increased morbidity, mortality, and increased length of stay whatever the admission specialty, thereby increasing costs of inpatient care.2Health and Social Care Information CentreNational Diabetes Inpatient Audit. 2011http://www.hscic.gov.uk/article/2021/Website-Search?productid=7285Google Scholar The perioperative mortality rate for people with diabetes is reported to be up to 50% higher than the non-diabetic population,3Frisch A Chandra P Smiley D et al.Prevalence and clinical outcome of hyperglycemia in the perioperative period in noncardiac surgery.Diabetes Care. 2010; 33: 1783-1788Crossref PubMed Scopus (412) Google Scholar the reasons being multifactorial,4Dhatariya K Levy N Flanagan D et al.for the Joint British Diabetes SocietiesManagement of adults with diabetes undergoing surgery and elective procedures: improving standards. Revised September. 2015http://www.diabetologists-abcd.org.uk/JBDS/JBDS_IP_Surgical_Guideline_2015_Full.pdfGoogle Scholar many of which are modifiable. Thus the emergency surgical patient with diabetes is often classified as being high risk. Articles have been published in an effort improve the outcome of the elective surgical patient with diabetes4Dhatariya K Levy N Flanagan D et al.for the Joint British Diabetes SocietiesManagement of adults with diabetes undergoing surgery and elective procedures: improving standards. Revised September. 2015http://www.diabetologists-abcd.org.uk/JBDS/JBDS_IP_Surgical_Guideline_2015_Full.pdfGoogle Scholar5Barker P Creasey P Dhatariya K et al.Peri-operative management of the surgical patient with diabetes.Anaesthesia. 2015; 70: 1427-1440Crossref PubMed Scopus (138) Google Scholar with the emergency surgical patient with diabetes being largely ignored. The purpose of this article is to redress that balance. The emergency surgical patient with diabetes is recognized to be at higher risk of complications. This is due to a number of factors including: Patients requiring emergency surgery with diabetes will often have co-existing microvascular and macrovascular complications, and then by definition will often have an ASA grade of risk of at least grade IIIE. The immediate/urgent emergency surgical patient with diabetes should always have their comorbidities assessed and any necessary precautions and actions taken to prevent deterioration. This may involve critical care, or other specialists e.g. cardiologists if the patient has an implantable cardioverter defibrillator. Furthermore, recent papers3Frisch A Chandra P Smiley D et al.Prevalence and clinical outcome of hyperglycemia in the perioperative period in noncardiac surgery.Diabetes Care. 2010; 33: 1783-1788Crossref PubMed Scopus (412) Google Scholar6Kwon S Thompson R Dellinger P Yanez D Farrohki E Flum D. Importance of perioperative glycemic control in general surgery: a report from the surgical care and outcomes assessment program.Ann Surg. 2013; 257: 8-14Crossref PubMed Scopus (354) Google Scholar have demonstrated a significant association between perioperative hyperglycaemia and the medical and infective complications of surgery [e.g. acute kidney injury (AKI), acute coronary syndromes, cerebro-vascular accidents, wound infections, and systemic infections]. These data provide impetus to ensure glycaemic control between 6.0 and 10.0 mmol litre−1. It is widely recognized that the surgical patient with diabetes has an increased risk of surgical site infection (SSI). It is also becoming increasingly recognized that diabetes and the degree of perioperative glycaemic control is a risk factor for both SSI and systemic infections.3Frisch A Chandra P Smiley D et al.Prevalence and clinical outcome of hyperglycemia in the perioperative period in noncardiac surgery.Diabetes Care. 2010; 33: 1783-1788Crossref PubMed Scopus (412) Google Scholar6Kwon S Thompson R Dellinger P Yanez D Farrohki E Flum D. Importance of perioperative glycemic control in general surgery: a report from the surgical care and outcomes assessment program.Ann Surg. 2013; 257: 8-14Crossref PubMed Scopus (354) Google Scholar Most authorities therefore suggest that glycaemic control throughout the whole of the hospital stay should be kept between 6.0 and 10.0 mmol litre−1,4Dhatariya K Levy N Flanagan D et al.for the Joint British Diabetes SocietiesManagement of adults with diabetes undergoing surgery and elective procedures: improving standards. Revised September. 2015http://www.diabetologists-abcd.org.uk/JBDS/JBDS_IP_Surgical_Guideline_2015_Full.pdfGoogle Scholar, 5Barker P Creasey P Dhatariya K et al.Peri-operative management of the surgical patient with diabetes.Anaesthesia. 2015; 70: 1427-1440Crossref PubMed Scopus (138) Google Scholar, 6Kwon S Thompson R Dellinger P Yanez D Farrohki E Flum D. Importance of perioperative glycemic control in general surgery: a report from the surgical care and outcomes assessment program.Ann Surg. 2013; 257: 8-14Crossref PubMed Scopus (354) Google Scholar, 7Moghissi ES Korytkowski MT Dinardo MM et al.American Association of Clinical Endocrinologists and American Diabetes Association consensus statement on inpatient glycemic control.Diabetes Care. 2009; 32: 1119-1131Crossref PubMed Scopus (918) Google Scholar and this target zone should be aimed for during surgery. Hyperglycaemia [defined as a capillary blood glucose (CBG) >10 mmol litre−1] is associated with excess morbidity and mortality caused by SSI, systemic infections, and other medical complications.3Frisch A Chandra P Smiley D et al.Prevalence and clinical outcome of hyperglycemia in the perioperative period in noncardiac surgery.Diabetes Care. 2010; 33: 1783-1788Crossref PubMed Scopus (412) Google Scholar6Kwon S Thompson R Dellinger P Yanez D Farrohki E Flum D. Importance of perioperative glycemic control in general surgery: a report from the surgical care and outcomes assessment program.Ann Surg. 2013; 257: 8-14Crossref PubMed Scopus (354) Google Scholar Conversely, hypoglycaemia (as defined as CBG < 4 mmol litre−1) is associated with excess mortality and extra length of stay. Worryingly, this excess mortality is now being observed in patients once their CBG is <6 mmol litre−1.8NICE-Sugar Study InvestigatorsHypoglycemia and risk of death in critically ill patients.N Engl J Med. 2012; 367: 1108-1118Crossref PubMed Scopus (682) Google Scholar It is therefore vital that in-patients with diabetes have the frequency of blood sugar monitoring and the treatment of hypoglycaemia and hyperglycaemia prescribed on admission. Furthermore about 22% of in-patients with diabetes will suffer at least one episode of hypoglycaemia during their hospital stay.1Health and Social Care Information CentreNational Diabetes Inpatient Audit (NaDIA), open data—2013. 2014http://www.hscic.gov.uk/catalogue/PUB14358Google Scholar2Health and Social Care Information CentreNational Diabetes Inpatient Audit. 2011http://www.hscic.gov.uk/article/2021/Website-Search?productid=7285Google Scholar Patients may present to hospital with diabetic ketoacidosis (DKA) secondary to surgical pathology and may subsequently require emergency surgery. Additionally, DKA from other causes may mimic the acute abdomen and may lead to unnecessary emergency surgery. Lack of administration of insulin to in-patients with Type 1 diabetes mellitus will result in hospital acquired DKA, and approximately 0.6% of in-patients with diabetes develop this preventable condition.1Health and Social Care Information CentreNational Diabetes Inpatient Audit (NaDIA), open data—2013. 2014http://www.hscic.gov.uk/catalogue/PUB14358Google Scholar Hospital acquired DKA in a recent national survey was the third leading precipitant of DKA (7.8%), with the two leading causes being infections (44.6%) and non-compliance (19.7%).9Dhatariya KK Nunney I Higgins K Sampson MJ Iceton G. A national survey of the management of diabetic ketoacidosis in the UK in 2014.Diabet Med. 2016; 33: 252-260Crossref PubMed Scopus (65) Google Scholar For many emergency surgical patients with diabetes, their glucose control is managed by the variable rate i.v. insulin infusion (VRIII) previously known as ‘the sliding scale’. The premise is that the patient receives a constant supply of substrate (usually 5 or 10% dextrose at approximately 100 ml h−1), and simultaneously receives an i.v. insulin infusion which is titrated to the CBG levels, and hence theoretically the CBG is controlled. Prior to its introduction the VRIII was never subjected to rigorous safety/efficacy studies, and only now is the level of harm associated with the VRIII being recognized.1Health and Social Care Information CentreNational Diabetes Inpatient Audit (NaDIA), open data—2013. 2014http://www.hscic.gov.uk/catalogue/PUB14358Google Scholar2Health and Social Care Information CentreNational Diabetes Inpatient Audit. 2011http://www.hscic.gov.uk/article/2021/Website-Search?productid=7285Google Scholar Strategies that either limit the unnecessary use of the VRIII or make the use of the VRIII safer are intrinsic to the goal of reducing complications associated with the management of emergency surgical patient with diabetes. It is now recognized that while insulin has the potential to be lifesaving, it also has the potential to cause harm and death through careless prescribing and administration.10National Patient Safety AgencySafer administration of insulin. 2010http://www.nrls.npsa.nhs.uk/resources/type/alerts/?entryid45=74287Google Scholar Harm from insulin mis-prescribing/maladministration is now classified as one of NHS England's ‘Never Events’. There are nearly 100 types of insulin/insulin delivery devices in the UK, and it is essential that the brand name is prescribed, accurately stating the amount of insulin to be administered in units (with the word ‘units’ written in full), and that the times of administration are unambiguously recorded. The administering nurse must ensure that the insulin is administered correctly, and always use a dedicated insulin syringe. It is becoming increasingly recognized that the paternalistic approach to in-patient healthcare can be detrimental, and when and where possible patients with diabetes should be encouraged to self-medicate.11Joint British Diabetes Societies Inpatient Care GroupSelf management of diabetes in hospital. 2012http://www.diabetologists-abcd.org.uk/JBDS/JBDS_IP_Self-Management.pdfGoogle Scholar Patients with diabetes are often prescribed several medications and the potential for either significant drug interactions or side effects is very real,1Health and Social Care Information CentreNational Diabetes Inpatient Audit (NaDIA), open data—2013. 2014http://www.hscic.gov.uk/catalogue/PUB14358Google Scholar2Health and Social Care Information CentreNational Diabetes Inpatient Audit. 2011http://www.hscic.gov.uk/article/2021/Website-Search?productid=7285Google Scholar e.g. an elderly patient with diabetes who has a fractured neck of femur and taking ramipril. The patient could develop AKI as a result of the administration of nephrotoxic drugs e.g. aminoglycosides, non-steroidal anti-inflammatory agents or due to deleterious effect of the ramipril being compounded by the low output state caused by either blood loss or intra-operative hypotension. The medical team need to be aware of these issues, and either takes precautions to ensure harm does not occur, or be vigilant and treat early and appropriately. Repeated National Confidential Enquiries into patient outcome and death (NCEPOD) studies have demonstrated that fluid and electrolyte mismanagement is common in both the elective and emergency surgical patient and is a major cause of morbidity and mortality. Subsequently the National Institute for Health and Care Excellence (NICE) was commissioned to create guidance in order to improve fluid and electrolyte management of in-patients.12National Institute for Clinical and Healthcare ExcellenceIntravenous fluid therapy in over 16s in hospital. 2013http://www.nice.org.uk/guidance/cg174Google Scholar The surgical patient with diabetes requiring emergency surgery is at higher risk of AKI13National Institute for Clinical and Healthcare ExcellenceAcute kidney injury: prevention, detection and management of acute kidney injury up to the point of renal replacement therapy (CG169). 2013https://www.nice.org.uk/guidance/cg169Google Scholar and fluid and electrolyte complications due to: (i)Co-morbidity e.g. pre-existing renal and cardiac impairment.(ii)Polypharmacy including nephrotoxic agents; diuretics and drugs causing electrolyte disturbances including insulin.(iii)Use of the VRIII demanding the use of concurrent substrate solutions containing glucose which predispose to hyponatremia.(iv)Use of the VRIII promoting intracellular potassium uptake and predisposing to hypokalaemia. The patient with diabetes is at risk of developing pressure ulcers, which may lead to extra morbidity and prolonged length of stay.4Dhatariya K Levy N Flanagan D et al.for the Joint British Diabetes SocietiesManagement of adults with diabetes undergoing surgery and elective procedures: improving standards. Revised September. 2015http://www.diabetologists-abcd.org.uk/JBDS/JBDS_IP_Surgical_Guideline_2015_Full.pdfGoogle Scholar For many years, the emergency operating list has been run by non-consultants and patients are operated on in the order of being ‘booked’, unless the patient requires immediate surgery. This has major repercussions including: (i)Unknown time of surgery with major delays and postponements.(ii)Prolonged and unpredictable starvation periods prior to surgery.(iii)Variable length of anaesthetic and surgical time due to lack of seniority of surgical and anaesthetic staff.(iv)Variable utilization of ‘fast track’ surgical and anaesthetic techniques that promote prompt eating, drinking, and mobilization.(v)Inability to utilize the standard comprehensive care pathway for management of the elective patient with diabetes purely due to the above reasons, resulting in reliance on the VRIII to manage the excessive period of starvation. In 2013 a snapshot survey in the UK estimated that 3 236 300 anaesthetics were administered by anaesthetists, with 965 100 being emergency procedures.14Sury MR Palmer JH Cook TM Pandit JJ. The state of UK anaesthesia: a survey of National Health Service activity in 2013.Br J Anaesth. 2014; 113: 575-584Abstract Full Text Full Text PDF PubMed Scopus (111) Google Scholar Therefore, it can be estimated that at least 100 000 emergency surgical procedures are performed on patients with diabetes each year (taking the conservative estimate that 10% of the emergency surgical population has diabetes). The snapshot survey also examined the classification of emergency performed using the NCEPOD classification.15National Confidential Enquiry into Patient Outcome and DeathNCEPOD revised classification of operation. 2004http://www.ncepod.org.uk/classification.htmlGoogle Scholar These data and the extrapolated caseload (assuming that 10% of the emergency surgical population has diabetes) is shown in Table 1.Table 1Estimated annual caseload of emergency procedures using NCEPOD classificationNumber of patients requiring emergency surgery%Approximate number of patients with diabetes (assuming approximately 10% prevalence of diabetes in the population requiring emergency surgery)Immediate85 80099 000Urgent680 4007070 000Expedited198 9002120 000Total965 10099 000 Open table in a new tab Immediate life, limb or organ-saving intervention—resuscitation simultaneous with intervention. Normally within minutes of the decision to operate. Intervention for acute onset or clinical deterioration of potentially life-threatening conditions, for those conditions that may threaten the survival of limb or organ. Normally within hours of decision to operate. Patient requiring early treatment where the condition is not an immediate threat to life, limb or organ survival. Normally within days of decision to operate. Intervention planned or booked in advance of routine admission to hospital. Timing to suit patient, hospital, and staff. It is now becoming increasingly recognized that having definitive patient pathways leads to improved patient outcome in the elective surgical patient. The care pathway for the perioperative management of the emergency surgical patient is more complicated than the linear elective pathway purely because there are several ways for the patient to commence the journey. The pathway is summarized in Figure 1. Despite the complexity of the admission process, Figure 1 highlights the opportunities for anaesthetists to influence and improve the perioperative management of the surgical patient with diabetes requiring emergency surgery (and indeed any other co-morbidity). The pathway for the emergency surgical patient with diabetes is at first appearance complicated. The principles are16Royal College of AnaesthetistsGuidance on the Provision of Emergency Anaesthesia Services. 2016http://www.rcoa.ac.uk/system/files/GPAS-2016-05-EMERGENCY.pdfGoogle Scholar: (i)Assess the need for immediate resuscitation.(ii)Perform resuscitation if required in parallel with further assessment.(iii)Assess the urgency of surgery.(iv)Assess co-morbidities.(v)Assess current glycaemic control with CBG and ketone levels.(vi)Assess need for the VRIII and prescribe correctly.(vii)Prescribe appropriate substrate fluids to run alongside VRIII (usually 5% glucose in 0.45% saline with premixed 0.15% potassium chloride).(viii)Prescribe appropriate resuscitative fluids.(ix)Ensure emergency treatment for hypoglycaemia and hyperglycaemia is prescribed.(x)Define frequency of CBG monitoring (hourly if on the VRIII).(xi)Define initial method of glycaemic control that is by either the VRIII; or manipulation of normal diabetes medication; or by fixed rate i.v. insulin infusion (FRIII) if the patient has DKA.(xii)Assess need for optimization, and then optimize, but not if this delays lifesaving surgery. Optimization in theatre suite should be considered if required.(xiii)Assess risk of perioperative AKI, and manage appropriately.(xiv)Perform appropriate medicine reconciliation and withhold drugs as appropriate (e.g. NSAIDs; ACE inhibitors; metformin and sulphonylureas).(xv)Perform risk assessment and identify the high-risk patient to assess level of care required postoperatively.(xvi)Perform risk assessment for mortality and make the risk explicit to the patient and ensure that this is recorded clearly on the consent form and in the medical record.(xvii)Assess level of anaesthetic and surgical seniority required at surgery.(xviii)The decision to operate on high-risk patients should be made at consultant level, involving surgeons and those who will provide intra and postoperative care.(xix)Discuss and agree with the patient the postoperative analgesic strategy.(xx)Involve diabetologists and diabetic inpatient specialist nurses (DISNs) in the management of the patient in order to reduce excess length of hospital stay.17Flanagan D Moore E Baker S Wright D Lynch P. Diabetes care in hospital—the impact of a dedicated inpatient care team.Diabet Med. 2008; 25: 147-151Crossref PubMed Scopus (63) Google Scholar Mandatory investigations generally include CBG; ketone levels; urea, creatinine, and electrolytes; full blood count and ECG. Arterial blood gases (ABG) and lactate may be indicated to allow scoring of severity of illness. Other investigations e.g. clotting studies; blood cultures; group and screen to be guided by clinical picture. A CBG will guide whether the patient needs urgent glycaemic control, as it is recognized that poor preoperative glycaemic control is associated with a poorer outcome. Capillary ketone levels >3 mmol litre−1 will indicate that the patient has developed DKA. DKA in the surgical patient may be caused by surgical pathology, or may cause symptoms of the acute abdomen and therefore senior review is mandatory. Only once a full and detailed assessment has been made can the patient be categorized as requiring expedited surgical care, urgent surgical care or immediate surgical care. The patient should be prioritized to prevent needless excessive starvation, which would contribute to glycaemic variability, and ideally should be given a realistic time for surgery. In the UK, the VRIII is the standard way of managing diabetes perioperatively. It should be used in the following circumstances: (i)Patient with Type 1 diabetes undergoing surgery with a starvation period greater than 1 missed meal.(ii)Patient with Type 1 diabetes undergoing surgery who has not received background insulin.(iii)Patient with Type 2 diabetes undergoing surgery with a starvation period greater than 1 missed meal and develops significant hyperglycaemia (CBG > 12 mmol litre−1).(iv)Patients with poorly controlled diabetes as defined as a HbA1c > 8.5% (69 mmol mol−1). Many surgical patients with diabetes requiring emergency surgery will fall into one of these brackets and thus will require a VRIII. As the VRIII is associated with many complications it is imperative that every hospital has comprehensive guidelines to facilitate its safe use. Box 1 highlights the salient points of safe use of the VRIII. Box 1The salient points in the safe use of the VRIIIAs the use of the VRIII is associated with multiple incidents including: •Hypoglycaemia.•Hyperglycaemia.•Ketosis because of either delayed establishment or delayed administration of sub cutaneous insulin on discontinuation.•Hyponatraemia.•Hypokalaemia.It is, therefore, imperative that the following is performed: •In patients with type 1 DM, the establishment of the VRIII must never be delayed once the decision is made to manage the diabetes with i.v. insulin rather than s.c.•The VRIII and the substrate solution must be administered through a dedicated cannula which includes appropriate anti-syphon one-way valves. No other drugs or fluids should be administered through this dedicated cannula.•Hourly monitoring of CBG to maintain ‘the range’ of 6–10 mmol litre−1.•The substrate infusion is never inadvertently stopped, for example, during transfers.•All hospitals must have guidelines for the safe use of the variable rate i.v. insulin infusion.•It is now recognized that the use of the VRIII may often cause hypoglycaemia; furthermore this may be because the many scales previously promoted a target zone of 4–8 mmol litre−1, and there was no safety buffer zone between safe and dangerous use. Therefore it is now advised that the scales be redesigned to promote all blood sugars to remain in the 6–10 mmol litre−1 zone.•As the half-life of soluble insulin is approximately 5 min, within 30 min of stopping a VRIII there will be no appreciable functioning insulin. If the patient has Type 1 DM, DKA will ensue. Therefore, in Type 1 DM patients the VRIII must never be taken down until alternative sub-cutaneous insulin has been administered.•The Hospital Diabetic specialist nurse or diabetologist should be involved if there are concerns in transferring the patient off the VRIII.Fluids to run alongside the VRIII•The initial maintenance solution to be used alongside the VRIII is 5% dextrose in 0.45% saline with additional potassium chloride at a rate of about 1–1.25 ml kg−1 h−1 up to a maximum of 90 ml h−1. The practice of alternating 5% glucose with 0.9% saline according to serum glucose is not recommended.•To prevent hypoglycaemia, the substrate solution containing glucose must never be discontinued inadvertently, especially during transfers.•Additional resuscitative fluids if required should be administered through a second cannula/central venous cannula and follow NICE CG 174 (i.v. fluid therapy in adults in hospital).•Continuous administration of substrate fluid with glucose to permit continuous administration of insulin is mandatory in starved patients with T1DM, however this may not be the case in patients with T2DM. Some cardiac centres are running their i.v. insulin infusions to patients with T2DM with no additional glucose in the fluids. Likewise, patients that are established on TPN in critical care generally do not require additional substrate solution.Treatment of CBG <4 mmol litre−1 whilst on VRIII•Reduce insulin rate accordingly.•Administer 100 ml of 20% glucose.•Recheck glucose every 15 min until CBG >6 mmol litre−1, and then revert to hourly.Management of CBG 4.1–6 mmol litre−1•Reduce insulin rate accordingly.•Administer 50 ml of 20% glucose i.v. to prevent the CBG falling to below 4.0 mmol litre−1.•Fastidiously recheck glucose every hour to ensure CBG does not fall below 4 mmol litre−1. As the use of the VRIII is associated with multiple incidents including: •Hypoglycaemia.•Hyperglycaemia.•Ketosis because of either delayed establishment or delayed administration of sub cutaneous insulin on discontinuation.•Hyponatraemia.•Hypokalaemia. It is, therefore, imperative that the following is performed: •In patients with type 1 DM, the establishment of the VRIII must never be delayed once the decision is made to manage the diabetes with i.v. insulin rather than s.c.•The VRIII and the substrate solution must be administered through a dedicated cannula which includes appropriate anti-syphon one-way valves. No other drugs or fluids should be administered through this dedicated cannula.•Hourly monitoring of CBG to maintain ‘the range’ of 6–10 mmol litre−1.•The substrate infusion is never inadvertently stopped, for example, during transfers.•All hospitals must have guidelines for the safe use of the variable rate i.v. insulin infusion.•It is now recognized that the use of the VRIII may often cause hypoglycaemia; furthermore this may be because the many scales previously promoted a target zone of 4–8 mmol litre−1, and there was no safety buffer zone between safe and dangerous use. Therefore it is now advised that the scales be redesigned to promote all blood sugars to remain in the 6–10 mmol litre−1 zone.•As the half-life of soluble insulin is approximately 5 min, within 30 min of stopping a VRIII there will be no appreciable functioning insulin. If the patient has Type 1 DM, DKA will ensue. Therefore, in Type 1 DM patients the VRIII must never be taken down until alternative sub-cutaneous insulin has been administered.•The Hospital Diabetic specialist nurse or diabetologist should be involved if there are concerns in transferring the patient off the VRIII. •The initial maintenance solution to be used alongside the VRIII is 5% dextrose in 0.45% saline with additional potassium chloride at a rate of about 1–1.25 ml kg−1 h−1 up to a maximum of 90 ml h−1. The practice of alternating 5% glucose with 0.9% saline according to serum glucose is not recommended.•To prevent hypoglycaemia, the substrate solution containing glucose must never be discontinued inadvertently, especially during transfers.•Additional resuscitative fluids if required should be administered through a second cannul