The effects of diabetes medications on post-operative long bone fracture healing

Diabetes has long been known to have an impact on bone repair. More recently, however, most diabetic patients receive medications to normalise this hyperglycaemic environment. To date, no studies have investigated the effects of diabetic medications on fracture healing in humans.

Patients were identified from two tertiary trauma centres. Inclusion criteria were adult patients having sustained a closed diaphyseal femoral or tibial fracture, treated surgically. Exclusion criteria were open, pathological or peri-prosthetic fractures, and patients having sustained polytrauma. Matched non-diabetic controls were identified, matched for age, sex, fracture classification and osteosynthesis. Output measures were: time to callus first appearance, bridging of involved cortices and time to union, along with the eventual outcome: union/non-union.

A total of 36 (25 males) eligible patients were identified with a control group of 166 patients (138 males). ANOVA demonstrated class of medication to have a significant effect at two of the three time points and on the eventual outcome. Multiple regression analysis also demonstrated significant impact (p = 0.02).

All classes of medication demonstrated anti-osteogenic effects compared to the control cohort. Biguanides demonstrated this in contrast to the in vitro evidence to date. Sulphonylureas demonstrated this to a greater extent; however, no in vitro evidence is available for comparison within this class. Clinicians should be aware of these delays in bone healing when treating diabetic patients and aim for optimal blood glucose control until such time as further research can be undertaken.