Does intensive glycaemic control promote healing in diabetic foot ulcers? - a feasibility study

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.