We are investigating associations between variations in candidate genes on chromosome 7q and diabetes-related phenotypes in Canadian Oji-Cree. One of these genes encodes the skeletal muscle regulatory G subunit of the glycogen-associated form of protein phosphatase 1 (PPPIR3), which may play a key role in muscle glycogen metabolism. There is a common 5-bp insertion-deletion polymorphism in a messenger ribonucleic acid-stabilizing AU(AT)-rich element within the 3'-untranslated region (UTR) of PPPIR3. The D allele had a frequency of 0.30 in the Oji-Cree. We found that this 3'-UTR variation of PPPIR3 was significantly associated with variation in 2-h postprandial glucose in adult Oji-Cree with type 2 diabetes or impaired glucose tolerance (IGT). Specifically, Oji-Cree with diabetes or IGT who were D/D homozygotes had significantly lower 2-h postprandial plasma glucose than subjects with the other genotypes. There was no association of the PPPIR3 genotype either with the presence of type 2 diabetes or IGT or with other quantitative traits in this sample. These findings suggest that common PPPIR3 3'-UTR variation that potentially affects messenger ribonucleic acid stability is associated with variation in glycemia in Oji-Cree subjects with type 2 diabetes.