Endocrine Abstracts

Background: Few cases have been described with a new-onset or worsening of a pre-existing diabetes mellitus in patients diagnosed with a renal cell carcinoma and amelioration of their diabetes following tumour resection.

Methodology: This is a retrospective study (2003-2021) including adult cases who were diagnosed with a renal cell carcinoma, who underwent tumour resection and whom glycemic control was monitored. HbA1c was measured at 3 time intervals; 18 months pre-operative, 6 months pre-operative and 6 months postoperative. Furthermore BMI, antidiabetic treatment and tumour characteristics were collected. The Fuhrman grading system (FGS), ranging from 1 to 4, is the most widely used pathological classification and predictor of renal cell carcinoma prognosis. A difference in HbA1c of 0.3% was considered clinically significant.

Results: In total, 12 cases (83% men) with a mean age of 66±9 years were included. Two cases had metastases. Seven cases had a clear renal cell carcinoma, 4 a papillary renal cell carcinoma and 1 a chromophobe renal cell carcinoma. None of the cases had a new-onset diabetes. One case with a chromophobe renal cell carcinoma had type 1 diabetes and showed no worsening of the metabolic control despite having aggressive tumour characteristics (diameter 10 cm, FGS 3). Metabolic control stayed stable after nephrectomy, insulin doses were not reduced. Eight cases had type 2 diabetes. Five of this 8 cases had a worsening of glycemic control before diagnosis. All these cases had a clear cell carcinoma, besides 1 case with metastatic disease having a papillary renal cell carcinoma. This in contrast to the remaining 3 cases with type 2 diabetes without worsening of glycemic control having a papillary renal cell carcinoma. All the cases with a worsening of glycemic control pre-operatively showed a significant improvement after total tumour resection, as their BMI remained stable. In 1 case, insulin therapy was started before resection and could be reduced postoperatively. Three cases had no diabetes, however 1 case with a clear cell carcinoma revealed a clinically significant reduction of HbA1c postoperatively of whom BMI was unchanged. The FGS and tumour diameter were heterogeneously distributed between cases with or without deterioration of glycemic control.

Conclusion: We present the evolution of the glycemic control of 12 cases before and at diagnosis of renal cell carcinoma and after tumour resection. No case had a new-onset diabetes. The cases with a worsening and improvement of HbA1c pre- and postoperative, respectively, were all clear cell carcinoma compared to the remaining cases having a papillary or chromophobe renal cell carcinoma. Literature describes clear renal cell carcinoma tends to be more aggressive. In this case series these carcinoma were also associated with a worsening of glycemic control.