Post-Transplant Diabetes Terminology
Post-transplant diabetes is called "Posttransplantation Diabetes Mellitus" (PTDM), which describes the presence of diabetes in the posttransplant setting irrespective of the timing of diabetes onset. 1
Key Terminology Distinctions
The medical literature uses two primary terms to describe diabetes following organ transplantation, and understanding the distinction is clinically important:
Posttransplantation Diabetes Mellitus (PTDM)
- PTDM is the broader, more inclusive term that describes the presence of diabetes in the posttransplant setting regardless of when the diabetes developed 1
- This term encompasses all cases of diabetes after transplantation, including previously undiagnosed pretransplant diabetes 1
- PTDM is clinically significant as a major risk factor for cardiovascular disease and chronic kidney disease in solid-organ transplantation 1
New-Onset Diabetes After Transplantation (NODAT)
- NODAT is a more specific designation that describes only individuals who develop truly new-onset diabetes following transplant 1
- NODAT specifically excludes two groups: patients with pretransplant diabetes that was undiagnosed, and patients with posttransplant hyperglycemia that resolves by hospital discharge 1
- This term is more restrictive and used primarily in research settings 2, 3
Clinical Diagnostic Considerations
Timing of Formal Diagnosis
- A formal diagnosis of PTDM should only be made once the patient is stable on maintenance immunosuppression (usually at least 45 days after transplantation) and in the absence of acute infection 1
- This timing is critical because approximately 90% of kidney allograft recipients exhibit hyperglycemia in the first few weeks following transplant, but most cases of stress- or steroid-induced hyperglycemia resolve by hospital discharge 1
Preferred Diagnostic Testing
- The oral glucose tolerance test (OGTT) is considered the gold-standard test for diagnosing PTDM, particularly at 1 year posttransplant 1
- However, screening with fasting plasma glucose and/or A1C can identify high-risk individuals requiring further assessment and may reduce the overall number of OGTTs required 1
Common Clinical Pitfall
The most critical error is diagnosing PTDM too early in the posttransplant period. Early posttransplant hyperglycemia is extremely common but often transient, and premature diagnosis can lead to unnecessary long-term treatment and incorrect prognostic counseling 4. Always wait until the patient is clinically stable on maintenance immunosuppression before making a formal PTDM diagnosis 1.