Introduction One in four diabetes patients will develop a foot ulcer over their lifetime. The role of glycaemic control in the healing of foot ulcers in diabetes patients is not supported by randomised controlled trial (RCT) data.
Objectives To determine the feasibility of an RCT of glycaemic control with intensive insulin therapy in diabetic foot ulcer, by assessing: entry criteria, fasting capillary blood glucose (FCBG) medication satisfaction and sensitivity of different ulcer-healing endpoints to glycaemic control.
Design Two substudies: one cross-sectional and one single-arm prospective.
Setting Single-centre secondary care diabetic foot clinic in New Zealand.
Participants Substudy 1: 78 participants consisting of all people ≥18 years with a diabetic foot ulcer presenting to the clinic over 35 weeks in 2015.
Substudy 2: 15 participants from Substudy 1 consenting to intensive insulin therapy.
Intervention Substudy 1: None.
Substudy 2: Intensive insulin therapy with standard podiatry care over 24 weeks.
Outcome Substudy 1: Proportion of participants satisfying potential RCT entry criteria; medication satisfaction (Diabetes Medication Satisfaction).
Substudy 2: FCBG, index ulcer healing time, index ulcer size, health-related quality of life (HRQoL; EuroQol 5 Dimensions 5 Levels and Diabetic Foot Ulcer Scale-Short Form).
Results Proportion in Substudy 1 satisfying all entry criteria was 31% (95% CI 21 to 42). FCBG values decreased between baseline and study end (difference −3.7 mmol/L, 95% CI −6.5 to −0.8); 83% (95% CI 44 to 95) of ulcers healed by 24 weeks. FCBG correlated negatively with medication satisfaction. Ulcer area logarithm was most sensitive to FCBG changes, displaying significant negative correlation with HRQoL outcomes. Detecting a 30% between-group difference in this outcome (80% power, α=5%) requires 220 participants per arm, achievable within 1 year with 15 centres similar to study setting.
Conclusions An adequately powered RCT requires cooperation between a large number of centres. Ulcer area logarithm should be primary endpoint.
Trial registration number ANZCTR ACTRN12617001414303
- diabetic foot
- wound management
- statistics & research methods
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AD and ACV are joint first authors.
Contributors ACV and AD designed the study and co-wrote the manuscript with VB. AD oversaw the intervention and contributed to the discussion. ACV contributed to data management, data monitoring and analysis planning and conduct. DP contributed to statistical analyses. BM coordinated the research. RG and AN provided podiatric care and contributed to discussion. AD and ACV take responsibility for the contents of the article, study design, access to data and the decision to submit and publish the results.
Funding This work was supported by the Health Research Council of New Zealand’s Feasibility Study grant number 14/605.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval Ethics approval was given for the study by the New Zealand Northern A Health and Disability Ethics Committee, ethics approval number 14/NTA/195.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request.
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