Background: Type 2 diabetes (T2DM) is the leading cause of chronic kidney disease (CKD) nationally but the determinants of T2DM-associated CKD have not been well characterised.
Aim: To compare the baseline prevalence and associates of CKD in T2DM in the community-based Fremantle Diabetes Study Phases I (FDS1) and II (FDS2).
Patients and Methods: FDS1 included 1,296 T2DM subjects recruited between 1993 and 1996. FDS2 recruited 1,509 T2DM residents from the same postcode-defined area between 2008 and 2011. All biochemical testing was carried out in the same accredited laboratory with results calibrated to current FDS2 assays. Estimated glomerular filtration rate (eGFR) was estimated from the CKD-EPI equation. CKD risk was defined by the Kidney Disease Improving Global Outcomes 2012 categories. Generalized linear modelling (GLM) was used for multivariate analyses.
Results: At baseline, FDS2 participants were older (65.4±11.7 vs 64.0±11.3 years; P<0.001), more were males (51.8% vs 48.6%; P=0.034), and they had longer median [inter-quartile range] diabetes duration (8.0 [2.7-15.4] vs 4.0 [1.0-9.0] years; P<0.001) vs FDS1 subjects. Reflecting more intensive management in FDS2, HbA1c, systolic blood pressure (SBP), and serum lipid profiles were significantly better despite greater obesity (all P<0.001). Nearly 60% of FDS2 patients had normoalbuminuria vs 42% in FDS1, while 70% vs 65% had eGFR ≥60 ml/min/1.73m2 (P≤0.021). However, 0.2% had end-stage CKD in FDS1 vs 0.9% in FDS2 (P=0.025). CKD category ≥3 in the pooled cohorts was independently associated with older age, male sex, Aboriginality, longer diabetes duration, lower fasting glucose, higher HbA1c, ln(total:HDL-cholesterol ratio), ln(serum triglycerides) and SBP, retinopathy, peripheral neuropathy and prior cardiovascular disease. After adjusting for these factors, FDS1 participants had a 79% increased risk of CKD category ≥3 vs those in FDS2.
Conclusions: In the 15 years between phases, enhanced management has improved T2DM-associated nephropathy but the absolute number of cases of CKD remains high.