AIMS/HYPOTHESIS Peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1alpha) is a transcriptional coactivator implicated in insulin release by beta cells and in insulin resistance. Therefore, genetic variation of PPARGC1A could be implicated in the onset of type 2 diabetes. In this study, we examined whether the PPARGC1A gene locus is associated with type 2 diabetes mellitus. We also investigated its association with clinical and metabolic parameters in healthy and diabetic subjects.

METHODS After sequencing exons and their boundaries of the PPARGC1A gene, including the promoter region ( approximately 1.5 kb), we genotyped eight common single nucleotide polymorphisms (SNPs) in an association study comprising 762 unrelated patients with type 2 diabetes and 303 non-diabetic control patients. We divided the patients with type 2 diabetes into quartiles or three groups according to age at diagnosis of type 2 diabetes (early-onset: <40 years of age, average-onset: 40< or = <60 years, and late-onset: > or =60 years).

RESULTS There was no strong association between SNPs or haplotypes of PPARGC1A and type 2 diabetes. However, the SNPs of g.-1789G>A and g.-1437C>T were associated with the age at diagnosis of type 2 diabetes (p=0.042 and p=0.032, respectively). In addition, the promoter SNPs of g.-1789G>A and g.-1437C>T and the haplotypes ht2 (-1789A and -1437T) were significantly associated with early-onset type 2 diabetes (p=0.002, p=0.001 and p=0.001, respectively).

CONCLUSIONS/INTERPRETATION Our results suggest that PPARGC1A promoter polymorphisms are associated with age at diagnosis of type 2 diabetes and early-onset type 2 diabetes in the Korean population.