In the absence of renal disease, 20 year mortality risk in type 1 diabetes is comparable to that of the general population: a report from the Pittsburgh Epidemiology of Diabetes Complications Study

Abstract

Aims/hypothesis: The FinnDiane Study has reported that mortality in type 1 diabetes is not increased over a 7 year follow-up in the absence of renal disease (RD). Using the Pittsburgh Epidemiology of Diabetes Complications (EDC) Study population (n = 658) of childhood-onset type 1 diabetes (age <17 years), the present study sought to replicate and expand these findings to a 20 year follow-up (as of 1 January 2008) and examine cause of death by renal status.

Methods: At baseline (1986-1988), mean age and duration of diabetes were 28 and 19 years, respectively. RD was defined as an albumin excretion rate ≥20 μg/min from multiple samples and grouped as microalbuminuria (MA; 20-200 μg/min), overt nephropathy (ON; >200 μg/min), or end stage renal disease (ESRD; dialysis or renal transplantation).

Results: At baseline, 311 (47.3%) individuals had RD (MA 21.3%, ON 22.2% and ESRD 3.8%). During a median 20 year follow-up, there were 152 deaths (23.1%). Mortality was 6.2 (95% CI 5.2-7.2) times higher than expected, with standardised mortality ratios of 2.0 (1.2-2.8) for normoalbuminuria (NA); 6.4 (4.4-8.4) for MA; 12.5 (9.5-15.4) for ON; and 29.8 (16.8-42.9) for ESRD. Excluding those (n = 64) with NA who later progressed to RD, no significant excess mortality was observed in the remaining NA group (1.2, 0.5-1.9), whose deaths were largely unrelated to diabetes.

Conclusions/interpretation: These data confirm the importance of RD, including persistent microalbuminuria, as a marker of mortality risk and suggest that type 1 diabetes patients without renal disease achieve long-term survival comparable to the general population.

Figure 1

Survival plots based on Cox-adjusted analysis of EDC participants stratified for the presence and severity of albuminuria, both unadjusted (a) and adjusted (b), the presence of macrovascular disease (c), and the presence of proliferative retinopathy (d) at baseline. Panels b–d are adjusted for duration of diabetes, sex, race, WHR, HbA_1c, SBP, renal function (eGFR-MDRD), ever smoker, and the other complications not being presented (i.e., macrovascular disease, proliferative retinopathy, and/or renal damage). Other variables available to the model but not selected include: DBP, BP medication use, HDL and non-HDL cholesterol, and WBC count. Panel d not adjusted for renal damage status (albuminuria category)

Figure 1

Survival plots based on Cox-adjusted analysis of EDC participants stratified for the presence and severity of albuminuria, both unadjusted (a) and adjusted (b), the presence of macrovascular disease (c), and the presence of proliferative retinopathy (d) at baseline. Panels b–d are adjusted for duration of diabetes, sex, race, WHR, HbA_1c, SBP, renal function (eGFR-MDRD), ever smoker, and the other complications not being presented (i.e., macrovascular disease, proliferative retinopathy, and/or renal damage). Other variables available to the model but not selected include: DBP, BP medication use, HDL and non-HDL cholesterol, and WBC count. Panel d not adjusted for renal damage status (albuminuria category)

Figure 1

Survival plots based on Cox-adjusted analysis of EDC participants stratified for the presence and severity of albuminuria, both unadjusted (a) and adjusted (b), the presence of macrovascular disease (c), and the presence of proliferative retinopathy (d) at baseline. Panels b–d are adjusted for duration of diabetes, sex, race, WHR, HbA_1c, SBP, renal function (eGFR-MDRD), ever smoker, and the other complications not being presented (i.e., macrovascular disease, proliferative retinopathy, and/or renal damage). Other variables available to the model but not selected include: DBP, BP medication use, HDL and non-HDL cholesterol, and WBC count. Panel d not adjusted for renal damage status (albuminuria category)

Figure 1

Survival plots based on Cox-adjusted analysis of EDC participants stratified for the presence and severity of albuminuria, both unadjusted (a) and adjusted (b), the presence of macrovascular disease (c), and the presence of proliferative retinopathy (d) at baseline. Panels b–d are adjusted for duration of diabetes, sex, race, WHR, HbA_1c, SBP, renal function (eGFR-MDRD), ever smoker, and the other complications not being presented (i.e., macrovascular disease, proliferative retinopathy, and/or renal damage). Other variables available to the model but not selected include: DBP, BP medication use, HDL and non-HDL cholesterol, and WBC count. Panel d not adjusted for renal damage status (albuminuria category)