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.