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Fearon et al. Metab Target Organ Damage 2022;2:13 https://dx.doi.org/10.20517/mtod.2022.12 Page 3 of 13

Table 1. Role of different preoperative strategies for type 2 diabetes mellitus
Relative
Strategy Evidence Benefits Downsides
risk
Medications Moderate/high Low Guidelines available Side effects
Can be given in combination and individualised for patients’ other May require titration
co-morbidities, e.g., Obesity, Cardiovascular disease Variations in cost and
Long term management accessibility
Very-low- Low/moderate Low Non-invasive, non-pharmacological Requires a high level of
energy diet patient commitment
Not well understood or
widely supported
Can be expensive
Short term
Bariatric Low High Potentially long-term remission/improvement (sleeve Cost
procedure gastrectomy) Surgical complications
Eg, IGB, SG IGB - short term
IGB: Intragastric balloon; SG: sleeve gastrectomy.

for people with DM .
[14]

PREOPERATIVE
Prehabilitation before elective surgery (both for benign disease and cancer) is continuing to develop and
become a tool to improve postoperative outcomes. It may involve a single focus, such as a physical exercise
program, or it may be a multimodal program implementing changes in exercise, nutrition, and provision of
psychological support, with the intent to improve the persons’ functional capacity before surgery and
prepare them for the emotional and physical stress of surgery .
[15]

Preoperative optimisation of people with DM (both Type 1 and Type 2) needs to be carefully considered in
the context of other co-morbidities, such as obesity, cardiovascular disease and hypertension. Initiating
treatment can lead to hypoglycemic episodes, and there is an ongoing debate about the optimal target range
for capillary glucose levels, particularly perioperatively. The accepted preoperative HbA1c target above
which complications are more likely is 43 mmol/mol, and the point at which surgery should be postponed is
[16]
≥ 69 mmol/mol (UK) . The evidence is mixed for determining the impact of HbA1c on postoperative
morbidity and mortality; a number of meta-analyses in cardiac and non-cardiac surgery have shown a trend
toward increased complications; however, there was significant heterogeneity in the included studies
making it challenging to determine any definitive conclusions [17,18] . An overview of studies of preoperative
bridging interventions is provided in Table 2. A major limitation is that surgical outcomes following the
intervention are not provided.

Identification
Currently, The National Institute for Health and Clinical Excellence (NICE) guidelines do not recommend
[19]
screening surgical patients ; however, the CPOC guidelines suggest that preoperative assessment should
include an HbA1c check for all everyone, thus allowing identification of people with undiagnosed T2DM
and a reflection of glycaemic control for those who already had a diagnosis of T2DM. A retrospective study
from Garg et al. demonstrated the benefits of implementing a preoperative DM program. A simple HbA1c
check at a preoperative appointment followed by referral for those with HbA1c > 8% and access to a
postoperative diabetes service improved identification of T2DM, led to more frequent monitoring of blood
glucose levels and fewer episodes of inpatient hypoglycaemia (4.93% down to 2.48%), and reduced length of
[20]
stay .