Optimising HbA1c monitoring intervals in patients with type 2 diabetes based on glycaemic control status: a target...

The appropriate glycated haemoglobin (HbA1c) monitoring intervals for patients with type 2 diabetes mellitus (T2DM) remain unclear.

To determine appropriate HbA1c monitoring intervals for patients with T2DM across different glycaemic control categories.

A target trial emulation study using electronic health records obtained from the Hospital Authority of Hong Kong and death records from the Hong Kong Government Death Registry.

Adult patients who had T2DM between 2009 and 2012 were identified and grouped by baseline HbA1c levels as follows: <7.0% (<53 mmol/mol), 7.0%-7.9% (53-63 mmol/mol), 8.0%-8.9% (64-74 mmol/mol), and ≥9.0% (≥75 mmol/mol). A pre-specified target trial was emulated for each group to evaluate the impact of various HbA1c monitoring intervals on the risk of all-cause mortality and cardiovascular disease (CVD). For HbA1c <7.0%, the following intervals were compared: every 2-4 months, 5-8 months, 9-15 months, and 16-24 months. For HbA1c ≥7.0%, comparisons were made between intervals of 2-4 months, 5-8 months, and 9-24 months. Follow-up continued until the earliest occurrence of the outcome, death, or 31 December 2021.

The cohort comprised 183 078 patients. For those with HbA1c <7.0%, extending the HbA1c monitoring interval to every 16-24 months was not associated with higher risks of the assessed outcomes compared with intervals of 2-4 months. Among patients with baseline HbA1c 7.0%-7.9%, 9-24-month monitoring intervals versus 2-4-month intervals was associated with higher mortality risk: hazard ratio (HR) 1.10, 95% confidence interval (CI) = 1.05 to 1.15. Moreover, for those with HbA1c ≥8.0%, when compared with monitoring at 2-4-month intervals, monitoring every 5-8 months was associated with higher risk of mortality (HbA1c 8.0%-8.9%: HR 1.10, 95% CI = 1.04 to 1.16; HbA1c ≥9.0%: HR 1.25, 95% CI = 1.18 to 1.33). The corresponding HRs for CVD were 1.04 (95% CI = 0.98 to 1.10) and 1.09 (95% CI = 1.02 to 1.17), respectively.

For patients with T2DM and HbA1c <7.0%, monitoring can be extended to 1.5-2 years. For those with HbA1c 7.0%-7.9% and ≥8.0%, recommended intervals are 6 months and 3 months, respectively.