The Association of HbA1c Variability with 12 Week and 12 Month Outcomes on Diabetes Related Foot Ulcer Healing

Abstract

Introduction

This study aimed to determine the relationship between HbA_1c variability and foot ulcer healing at 12 weeks and 12 months.

Methods

Using National Diabetic Foot Care Audit (NDFA) and hospital records, demographics, baseline ulcer characteristics and healing outcomes for subjects presenting with a foot ulcer between 2017–2022 were collected at 12 weeks and 12 months. Subjects had diabetes duration > 3 years and ≥ 3 HbA_1c recordings in the 5 years prior to presentation.

Results

At 12 weeks, factors associated with an active ulcer were presence on hind foot (adjusted odds ratios) (2.1 [95% CI 1.3–3.7]), ischaemia (2.1 [95% CI:1.4–3.2]), area > 1 cm² (2.7 [95% CI:1.7–4.2]) and diabetes duration > 24 years vs 3–10 (AOR 2.0 [95% CI 1.2–3.5]). After adjustment, HbA_1c variability 6–10 mmol/mol and > 14.5 mmol/mol had AOR of 1.76 (95% CI 1.1–2.8; p = 0.0192) and 1.5 (95% CI 0.9–2.6; p = 0.1148) of an active ulcer at 12 weeks vs variability < 6 mmol/mol. At 12 months, ischaemia (AOR 2.4 [95% CI 1.5–3.8]) and diabetes duration > 24 years vs 3–10 years (AOR 3.3 [95% CI 1.7–6.4] were significant factors. HbA_1c variability was not significant at 12 months.

Conclusion

In keeping with the national NDFA data, in our cohort ulcer characteristics, but not HbA_1c variability, were the key factors associated with ulcer healing at 12 weeks and 12 months.

Plain Language Summary

Diabetes complications occur more frequently when glucose control is not as good as it could be. For a long time, HbA_1c, or glycated haemoglobin, has been used as a measure of how well someone’s diabetes has been controlled. However, another way of looking at diabetes control is to look at the changes of HbA_1c over time—this is called glycaemic variability. Diabetes-related foot disease is one of the most feared complications of the condition, and our group has previously shown in a small study that glycaemic variability was associated with ulcer healing at 12 weeks—with lower variability leading to better healing. However, it did not consider other variables known to be associated with not being alive and ulcer free at 12 months. In the UK, data are collected as part of the National Diabetes Footcare Audit (NDFA). This dataset collects a lot of information on new foot ulcers and their outcomes 12 weeks later. We have used our centre’s data to look at factors not included in the NDFA dataset—in particular glycaemic variability—to determine whether this influences ulcer outcomes at 12 weeks, but also at 12 months. We found that low glycaemic variability is associated with greater chances of healing but that the greatest association is the presence of poor blood flow and diabetes duration.