Lapice et al. (1) confirmed the findings in Chinese (2) or Caucasian patients (3) on the association between the peroxisome proliferator–activated receptor (PPAR)-γ2 Pro12Ala and urinary albumin excretion rate (AER) in a large population with type 2 diabetic patients (n = 750) of Caucasian origin. Moreover, they observed that the Ala12 carrier showed significantly lower plasma urea and creatinine (Scr) and higher estimated glomerular filtration rate (eGFR) than the Pro12 carrier (P < 0.05 for each) in the study.
In our study, there were significantly elevated Scr and blood urea nitrogen [i.e., 84.0 (64.0–129.0) vs. 64.0 (55.0–78.0) μmol/l (2) and 6.3 (5.1–9.1) vs. 5.6 (4.7–6.9) mmol/l, P = 0.000 for each], declined eGFR (77.6 ± 45.0 vs. 100.6 ± 29.7 ml/min/1.73 m2, P = 0.000), and Pro12Ala carriers (6.2% vs. 12.8%, P = 0.003) in diabetic nephropathy patients when compared with nondiabetic nephropathy patients (P < 0.01 for each) (2). In addition, except for the Pro12Ala patients who had lower AER levels than the Pro12Pro patients [9.22 (6.2–15.6) vs. 173.0 (69.9–691.1) mg/24 h, P = 0.000] (2), Pro12Ala patients had lower Scr and blood urea nitrogen trends [i.e., 68.0 (57.0–104.0) vs. 76.0 (60.0–105.8) μmol/l (2) and 6.0 (4.9–8.1) vs. 6.2 (4.8–8.7) mmol/l] and higher eGFR trend (87.2 ± 43.0 vs. 84.4 ± 42.3 ml/min/1.73 m2), but the differences were not statistically significant (P > 0.05 for each). Similarly, the occurrence of subjects with mildly impaired renal function (i.e., GFR <60 ml/min/1.73 m2) has a lower tendency in patients with the Pro12Ala than that of the Pro12Pro genotype (24.1% vs. 28.0%, P = 0.533; odds ratio 0.82 [95% CI 0.44–1.53]); however, no statistical significance was observed.
Previous studies reported that the Ala12 allele was resistant to type 2 diabetes in Caucasians but not in Chinese, thus reflecting an ethnic genetic heterogeneity of type 2 diabetes at this locus (4). No difference in Scr between Ala12 carriers and noncarriers was reported in Caucasian type 2 diabetic patients (3). Jorsal et al. (5) reported that the Ala12 allele is associated with enhanced decline in GFR (P = 0.04) in Danish Caucasian type 1 diabetic patients.
In conclusion, except for AER, the Pro12Ala polymorphism of PPAR-γ2 is not significantly associated with the overall better renal function in Chinese type 2 diabetic patients with and without diabetic nephropathy.
Acknowledgments
No potential conflicts of interest relevant to this article were reported.
L.L. researched the data, wrote the letter, and reviewed and edited the letter; T.Z. researched the data; F.W. reviewed the letter; N.W. reviewed the letter; and M.L. researched the data.
