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

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

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

Design & setting A target trial emulation study using electronic health records

Method Adult T2DM patients from 2009 to 2012 were identified and grouped by baseline HbA1c levels:<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 diseases (CVD). Compared intervals were every 2–4, 5–8, 9–15, and 16–24 months for HbA1c<7.0%, and every 2–4, 5–8, and 9–24 months for HbA1c≥7.0%. Follow-up continued until the earliest occurrence of the outcome, death, or December 31, 2021.

Results The cohort included 183,078 patients. For those with HbA1c<7%, extending the HbA1c monitoring interval to every 16-24 months did not increase the risk outcome compared to 2-4-month intervals. Patients with baseline HbA1c between 7-7.9% faced a significantly higher mortality risk when monitored at 9-24-month versus 2-4-month intervals (HR [95% CI]: 1.10 [1.05,1.15]). Moreover, for those with HbA1c≥8%, monitoring every 5-8 months increased the risk of mortality and/or CVD compared to 2-4-month intervals (HR [95% CI] for HbA1c 8-8.9%: 1.10 [1.04,1.16] for all-cause mortality, 1.04 [0.98,1.10] for CVD; HR [95% CI] for HbA1c≥9%: 1.25 [1.18,1.33] for all-cause mortality, and 1.09 [1.02,1.17] for CVD).

Conclusions For T2DM patients with HbA1c<7%, monitoring can be extended to 1.5–2 years. For those with HbA1c 7.0-7.9% and≥8%, recommended intervals are six and three months, respectively. (293 words)