843-P: The Variability in Glycosylated Haemoglobin (HbA1c) Testing Interval in People with Diabetes Is Closely Linked to Long-Term Diabetes Control

Worldwide guidance advocates regular HbA1c testing for people with diabetes, usually 2-4x/yr. Here we examine the effect of test interval variability (SD in test interval) on HbA1c change over 5yrs (Jun 2012-Jul 2019) using laboratory data. We focused on people with ≥6tests (23582 patients) over 5 years. We grouped cases based on the number of tests between t0 and t0+5yrs and calculated SDdecile for each group. We examined the link between SDdeciles and ΔHbA1c level, stratifying by starting HbA1c. We showed that higher variability in testing frequency links to worsening HbA1c control (Fig1). This effect was most evident in those with lower starting HbA1c levels(Fig1a-d). In those with a starting HbA1c 75mmol/mol, the same trends were seen. These effects were independent of testing interval. These findings indicate that testing consistency, not just numbers/yr, is critical to maintain diabetes control. This has implications for management of sporadic attenders. We need to develop systems to improve testing regularity. Disclosure A. A. Fryer: None. D. Holland: Other Relationship; Self; Siemens Corporation. M. Stedman: None. C. Duff: None. L. A. Green: None. J. Scargill: None. F. Hanna: None. P. Wu: None. A. H. Heald: None.