Glycated haemoglobin and the risk of postoperative complications in people without diabetes: a prospective population‐based study in UK Biobank

Abstract

Summary The aim of our study was to clarify the association between glycated haemoglobin (HbA1c) and postoperative outcomes in people without an existing diagnosis of diabetes. Half a million adults were recruited into the UK Biobank prospective cohort study between March 2006 and October 2010. We divided participants into three groups: no diagnosis of diabetes and HbA1c < 42 mmol.mol−1; no diagnosis of diabetes and elevated HbA1c (≥ 42 mmol.mol−1 with no upper limit); and prevalent diabetes (regardless of HbA1c concentration) at recruitment. We followed up participants by linkage with routinely collected hospital data to determine any surgical procedures undertaken after recruitment and the associated postoperative outcomes. Our main outcome measure was a composite primary outcome of 30‐day major postoperative complications and 90‐day all‐cause mortality. We used logistic regression to estimate the odds of the primary outcome by group. We limited analyses to those who underwent surgery within one year of recruitment (n = 26,653). In a combined effects logistic regression model, participants not known to have diabetes with HbA1c ≥ 42 mmol.mol−1 had increased odds of the primary outcome (OR [95% CI] 1.43 [1.02–2.02]; p = 0.04), when compared with those without diabetes and HbA1c < 42 mmol.mol−1. This effect was attenuated and no longer statistically significant in a direct effects model with adjustment for hyperglycaemia‐related comorbidity (OR [95% CI] 1.37 [0.97–1.93]; p = 0.07). Elevated pre‐operative HbA1c in people without diabetes may be associated with an increased risk of complications, but the association is likely confounded by end‐organ comorbidity. In contrast to previous evidence, our findings suggest that to prevent adverse postoperative outcomes, optimisation of pre‐existing morbidity should take precedence over reducing HbA1c in people without diabetes.

The Association Between Glycaemic Control, Renal Function and Post-operative Ophthalmic Complications in People With Diabetes Undergoing Cataract Surgery—A Single-Centre Retrospective Analysis

“…Our data are in line with recently published data from a UK Biobank study looking at the relationship between HbA 1c and the risk of postoperative complications in all forms of surgery. Those authors showed that, whilst the unadjusted risk of an adverse post-operative event was significant (OR [95% CI] 1.43 [1.02-2.02]; [18]. Diabetes causes macrovascular and microvascular complications, namely myocardial infarction, stroke, and renal, nerve and eye disease.…”

Finding the undiagnosed: should we screen for diabetes pre‐operatively?

“…Public Health England has estimated the prevalence of elevated HbA 1c levels without a formal diagnosis of (pre-) diabetes in the general population to be 13%, of which 2.3% will meet the diagnosis of diabetes [15]. Lam et al found a prevalence of elevated HbA 1c levels in only 5% of their study population, probably because the Biobank database represents a relatively young sample of the general population and not a surgical population [7]. The prevalence of elevated HbA 1c levels in the population presenting for surgery could be as high as 40% [1], meaning that a significant proportion of adult patients presenting for surgery may have an increased risk of postoperative complications.…”

“…To summarise, the study by Lam et al. [7] shows us that a substantial proportion of patients presenting for surgery have a higher risk of postoperative complications related to long‐term glycaemic control, also in HbA 1c ranges not diagnostic for diabetes. The association is largely driven by the presence of comorbidities, especially in patients with pre‐diabetes.…”

“…In this issue of Anaesthesia, Lam et al used data from the UK Biobank to assess the association between HbA 1c and postoperative complications and made a relevant distinction between patients with and without diabetes [7] They included 26,653 patients of whom 2093 (7.8%) had a diagnosis of diabetes, 1124 (4.2%) had pre-diabetes (HbA 1c 42-47 mmol.mol -1 ) and 181 (0.7%) had undiagnosed diabetes (HbA 1c ≥ 48 mmol.mol -1 ). Unfortunately, lack of power forced the authors to combine the latter two groups.…”

“…In this issue of Anaesthesia , Lam et al. used data from the UK Biobank to assess the association between HbA 1c and postoperative complications and made a relevant distinction between patients with and without diabetes [7]. The UK Biobank stores demographic data, socio‐economic factors, self‐reported medical conditions, risk‐factors and physical measures together with a biological sample.…”