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Page 2 of 13 Fearon et al. Metab Target Organ Damage 2022;2:13 https://dx.doi.org/10.20517/mtod.2022.12

Keywords: Diabetes mellitus, surgery, perioperative, calorie restriction, very-low-energy diet

INTRODUCTION
People with diabetes mellitus (DM) undergo more elective surgery due to macrovascular complications
such as coronary artery disease, peripheral vascular disease and kidney disease. Up to 50% of people with
DM require surgery, and patients referred for elective surgery may have a 50% higher prevalence than the
[1]
general population . Furthermore, as the prevalence of obesity increases, this also contributes to the
predicted increase in the prevalence of both diseases. Therefore, perioperative obesity and DM care must
continue to improve and be seen as an opportunity to diagnose and instigate treatment for both the
[2,3]
perioperative and long term .

Stress hyperglycaemia encompasses hyperglycaemia, insulin resistance and glucose intolerance.
Physiological changes include increased glucagon, adrenaline, cortisol, and growth hormone release leading
to increased glucose levels due to increased hepatic production and insulin resistance. This induces
[4]
increased oxidative stress and pro-inflammatory cytokine release . These changes occur in people with and
without DM, can occur after acute illness, injury, or surgery, and can be worse in those without DM. Stress
hyperglycaemia is associated with increased complications, increased mortality, and a longer hospital stay.
More recent data suggests this is not a causal effect and is likely an adaptive response to trauma to maintain
[5]
glucose transport to vital tissues . This is supported by studies demonstrating that efforts to intensively
manage glycaemic control during acute stress hyperglycaemia have been associated with worse clinical
outcomes . Acute stress hyperglycaemia may be beneficial; however, data also shows that chronic
[6]
hyperglycaemia leads to fluid shifts, renal overload, and fluid depletion . A stress hyperglycaemia ratio
[5]
(SHR) evaluating relative hyperglycaemia has been explored by Roberts et al., who report SHR as an
independent marker of critical illness. The authors found that the SHR was not different in people with
glycosylated haemoglobin (HbA1c) of more or less than 6.5 mmol .
[7,8]

This review aims to outline interventions for T2DM to prevent stress hyperglycaemia in people with DM,
particularly the use of very-low-energy diets, pharmacotherapy, and metabolic surgery as bridging
interventions [Table 1]. Elective surgery usually allows time to optimise clinical status for safer surgery.
Some strategies may also apply to people with type 1 diabetes (T1DM) and obesity, reducing insulin
resistance and/or improving glucose control.

SURGERY
Perioperative DM care is variable and often suboptimal. Furthermore, approximately 50% of people with
DM are undiagnosed; therefore, improving efforts to identify and instigate early treatment is crucial to
preventing long-term complications . There is global variation in criteria for diagnosis of DM and pre-DM
[9]
and variations in measurements and standards used for diagnosis and remission; this has been highlighted
as a particular safety issue in reporting for diabetic ketoacidosis . Previous studies have shown that people
[10]
with preoperatively diagnosed DM have better perioperative outcomes than those with unidentified
hyperglycaemia [11,12] . This reflects an improvement in glycaemic status and optimisation of other coexistent
diseases, such as cardiovascular disease. This is likely due to better control of other modifiable risk factors
and optimisation of coexistent conditions leading to a lower risk of acute myocardial infarction .
[13]

People with DM have a longer length of stay and higher postoperative complication rates than those
without DM. A comprehensive care pathway from the UK Centre for Perioperative Care (CPOC) was
published in March 2021 and provides guidelines on all aspects of care, from referral to discharge planning