The 5-time point oral glucose tolerance test as a predictor of new-onset diabetes after kidney transplantation

Aims

To evaluate the predictive power of the 5-time point oral glucose tolerance test (OGTT) for new-onset diabetes after kidney transplantation (NODAT).

Methods

We performed a retrospective study of 145 patients without diabetes who received kidney transplantations at our hospital. The 5-time point OGTT was performed before transplantation. The area under a receiver-operating characteristic curve (aROC) was used for evaluating the predictive power of 5-time point OGTT values.

Results

Seventeen patients developed NODAT within 1 year after transplantation. All postload plasma glucose (PPG) levels were higher in patients who developed NODAT than in those who did not; fasting plasma glucose levels were not different. The aROC for the area under the glucose concentration-time curve was significantly greater than that for fasting plasma glucose. Univariate and multivariate analyses showed that each PPG level was an independent risk factor for NODAT. Furthermore, patients with normal glucose tolerance (NGT) or impaired glucose tolerance (IGT) could be stratified with a 1-h plasma glucose (1h-PG) cut-off point of 8.4 mmol/L. The incidences of NODAT were 23.5%, 16.7%, 9.1%, and 0% for patients with IGT + 1h-PG ≥8.4 mmol/L,IGT + 1h-PG <8.4 mmol/L, NGT + 1h-PG ≥ 8.4 mmol/L, and NGT + 1h-PG < 8.4 mmol/L, respectively.

Conclusions

The area under the glucose concentration-time curve and each PPG concentration during the 5-time point OGTT are strong predictors of NODAT. A 1h-PG cut-off point of 8.4 mmol/L plus NGT/IGT can be used to identify patients at intermediate and high risk of developing NODAT.