New-onset diabetes after transplantation--role of oral glucose tolerance test for diagnosis and study of risk factors.

To determine the role of the oral glucose tolerance test in the early detection of new-onset diabetes after transplantation (NODAT) and to compare the various risk factors and insulin kinetics in the transplant patients, we studied 41 live-related renal allograft recipients who were not diabetic before transplantation. Immunosuppression included triple drug therapy (cyclosporine, azathioprine and steroids) and rejection episodes were treated with methyl prednisolone (30 mg/kg IV × 3 days). All the study patients were subjected to an oral glucose tolerance test (OGTT) at Day 90 post-transplant and classified as having normal glucose tolerance (NGT), impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and NODAT as per the World Health Organization guidelines. Insulin levels were also determined at 0, ½ hour, 1 hour and 2 hours during OGTT. NODAT was noted in 29.2% of the study patients, IFG in 4.8% of the study patients and NGT in 65.8% of the study patients. All the groups had normal fasting plasma glucose, but higher than normal insulin levels, suggesting insulin resistance. The patients with overt NODAT had, in addition, low fasting insulin (insulin secretory defect). OGTT may be used for the early detection of NODAT. Although insulin resistance is detected in the majority of post-transplant patients, NODAT also reveals also an insulin secretory defect.