Early Improvement of Unstable Diabetic Retinopathy After Solitary Pancreas Transplantation

Solitary pancreas transplantation (SPT) can significantly improve the quality of life of diabetic patients by eliminating the need for exogenous insulin, frequent home glucose monitoring, and many of the dietary restrictions imposed by the disease. In addition, successful SPT is able to eliminate acute diabetes complications, such as hypoglycemic and/or hyperglycemic episodes (1).

The effects of SPT on long-term complications of diabetes is less clear, but restoration of long-lasting normoglycemia seems to have several beneficial actions, including improvement of neuropathy and nephropathy (2). Little information is currently available on the role of SPT on the evolution of diabetic retinopathy. Ramsay et al. (3) studied the progression of retinopathy in solitary pancreas recipients and found some beneficial effect at 3 years after transplant.

An SPT program in type 1 diabetic patients has recently started in our center. Inclusion criteria are as recommended (1). In a group of nine patients (four men and five women who were aged 35 ± 10 years, had duration of diabetes of 24 ± 11 years, and received SPT with portal drainage), we evaluated the early effects of the transplant on unstable diabetic retinopathy, a condition characterized by a drop in visual acuity of at least 2 Snellen lines, and/or an episode of vitreous hemorrhage, and/or laser treatment and/or vitrectomy in the 2 years before transplantation (4).

Normalization of glucose levels with no exogenous insulin administration was quickly achieved and maintained by SPT. Fasting plasma glucose concentrations, HbA_1c levels, and C-peptide concentrations pretransplant and at 6 months postgrafting were 13.9 ± 0.4 and 4.6 ± 0.2 mmol/l, 9.1 ± 0.3 and 5.8 ± 0.1%, and 0.02 ± 0.00 vs. 3.2 ± 0.2 ng/ml, respectively (all P < 0.01). All of the patients were examined with corrected visual acuity, slit lamp examination, measurement of intraocular pressure, indirect and direct retinoscopy, and two nonstereoscopic 45° retinal photographs for each eye (4,5). Compared with pretransplant examination, at 6 months from SPT, two patients showed an improvement of visual acuity of >2 Snellen lines. The number of microaneurisms and microhemorrhages decreased, respectively, from 17 ± 4 to 9 ± 3 and from 12 ± 3 to 5 ± 2 per field (both P < 0.05). The number of hard hessudates did not change significantly (8 ± 2 vs. 7 ± 2 per field). Macular lesions of varying degree were present in six eyes (four patients) before transplantation and disappeared in five eyes (three patients) after 6 months from grafting. Intraocular pressure remained unchanged. No negative ocular event occurred in this early post-transplant follow-up.

The effects of pancreas transplantation on diabetic retinopathy are still controversial. In recent work (2,4), improvement or stabilization of advanced diabetic retinopathy was shown when the pancreas was transplanted together with a kidney to also treat renal insufficiency. Scant information is available as for the effects of solitary pancreas grafting on retinopathy in type 1 diabetic patients. In a previous article, a group of patients (most of them with proliferative retinopathy) were followed up to 3 years from SPT (3). At 2 years after SPT, the incidence of progression to a higher grade of retinopathy was the same in the eyes of recipients with versus without pancreas function. However, after 3 years, no further progression occurred in the patients with surviving graft, and 70% with failed pancreas transplants advanced to a higher grade of retinopathy by 5 years (2). In the present letter, we provide evidence of stabilization or improvement of pretransplant unstable retinopathy, early after pancreas transplantation. Although this finding needs to be confirmed in larger series, and long-term follow-up is obviously required, this is the first reported evidence that normalization of blood glucose levels in type 1 diabetic patients, as achieved by successful SPT, can quickly improve some lesions of diabetic retinopathy.