An unexpectedly high prevalence of undiagnosed diabetes in patients awaiting lung transplantation

BACKGROUND: Diabetes mellitus (DM) is a common complication after lung transplantation but its prevalence prior to transplantation has not been determined. We sought to determine the prevalence of and risk factors for DM in adults awaiting lung transplantation and to determine whether pre-transplant DM could be diagnosed by hemoglobin A1c (HbA1c) alone.

METHODS: All patients wait-listed for lung transplantation over a 2-year period had HbA1c measured. Those not known to have DM also underwent an oral glucose tolerance test (OGTT) with insulin levels.

RESULTS: Of 190 patients listed for lung transplantation, 30 (16%) had been diagnosed previously with DM. Twelve patients received transplants and 1 came off the waiting list before having an OGTT. The remaining patients underwent OGTT: 14 were newly diagnosed with DM and 29 with pre-diabetes. One patient vomited during the test and was excluded from analyses. Thus, 41% of all screened waiting list patients had DM (known or newly diagnosed) or pre-diabetes. Neither age, BMI, prednisolone dose nor family history correlated with dysglycemia. Patients with newly diagnosed DM and pre-diabetes were more insulin-resistant than those with normoglycemia. HbA(1c) correlated poorly with OGTT.

CONCLUSIONS: Patients awaiting lung transplantation have unexpectedly high rates of DM and prediabetes despite close medical follow-up. Screening for DM with an OGTT will allow early intervention, which may improve outcomes after transplantation.