Introduction New onset diabetes after transplantation (NODAT) is a well-known complication of immunosuppressive therapy and is associated with excess morbidity and mortality. Early identification and treatment of impaired glucose regulation (IGR) is crucial to help prevent or delay the development of NODAT and its associated complications.

Aim To define circadian glucose patterns of cardiothoracic transplant (CTTx) recipients using a continuous glucose monitoring system (CGMS) and compare the findings with conventional tests for diabetes.

Method Cross-sectional study in a CTTx outpatient clinic. CGMS was used to construct circadian glucose profiles. Those with CGMS values in excess of 7.7 mmol/l were asked to complete oral glucose tolerance tests (OGTT) and HbA1c.

Participants Convenience sampling was used to identify 12 stable CTTx recipients (2 heart, 3 single lung and 7 double lung Tx; 9 male; mean [SD] age 58 [8] years, BMI 28.6 [4.9] kg/m², daily prednisolone dose 11.5 [2.2] mg; 4 on tacrolimus vs 8 on cyclosporine; median 477 days since Tx).

Results None had symptoms of hyperglyaemia. CGMS duration range: 37 to 183 hrs/patient. A significant difference was seen between mean morning (06.00–12.00 hrs) and evening (14.00–20.00 hrs) glucose values (5.8 [1.2] vs 7.6 [1.4] mmol/l; p < 0.001, Figure 1). On CGMS data all participants had glucose values >7.7 mmol/l. Three (25%) had glucose values >11.1 and <3.5 mmol/l on CGMS and were diagnosed with impaired glucose tolerance on OGTT. Compared with 9 normal OGTT patients, the IGT group displayed a higher number of hyperglycaemic episodes/day and a greater% of time above 7.8 mmol/l. No cases of impaired fasting glycaemia or NODAT were identified using OGTT or HbA1c.

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Abstract S118 Figure 1

 

Conclusion Findings of this pilot study emphasise the importance of improving screening for IGR in CTTx recipients. We identified diurnal variation in glucose patterns, with higher glucose values in the afternoon and evening than morning, which has implications for timing of random glucose sampling in clinic. Poor correlation was found between CGMS and conventional diagnostic tests for diabetes which may not be sensitive enough to identify IGR in CTTx recipients. This merits further investigation in a larger cohort.