OBJECTIVE: To investigate the relationship between depression and diabetic nephropathy progression in type 1 diabetes.
RESEARCH DESIGN AND METHODS: Data from 3,730 participants without end-stage renal disease (ESRD) at baseline, participating in the Finnish Diabetic Nephropathy Study, were included. Depression was assessed in three ways. Depression diagnoses were obtained from the Finnish Care Register for Health Care. Antidepressant agent purchase data were obtained from the Drug Prescription Register. Symptoms of depression were assessed using the Beck Depression Inventory (BDI). Based on their urinary albumin excretion rate (AER), participants were classified as those with normal AER, microalbuminuria, and macroalbuminuria. Progression from normal AER to microalbuminuria, macroalbuminuria, or ESRD; from microalbuminuria to macroalbuminuria or ESRD; or from macroalbuminuria to ESRD, during the follow-up period, was investigated.
RESULTS: Over a mean follow-up period of 9.6 years, renal status deteriorated in 18.4% of the participants. Diagnosed depression and antidepressant purchases before baseline were associated with 53% and 32% increased risk of diabetic nephropathy progression, respectively. Diagnosed depression assessed during follow-up remained associated with increased risk of disease progression (32%). BDI-derived symptoms of depression showed no association with the progression, but the total number of antidepressant purchases modestly reduced the risk (hazard ratio 0.989 [95% CI 0.982-0.997]), P = 0.008). With the sample divided based on median age, the observations followed those seen in the whole group. However, symptoms of depression additionally predicted progression in those age ≤36.5 years.
CONCLUSIONS: Diagnosed depression and antidepressant purchases are associated with the progression of diabetic nephropathy in type 1 diabetes. Whether successful treatment of depression reduces the risk needs to be determined.