Abstract: Objective To examine the relationship of the K12 1Q polymorphism of membrane glycoprotein PC-1 gene with the features of insul in resistance (IR) and the development of T2DM in non-diabetic relatives. Methods We genotyped 216 type 2 diabetic patients, 133 non-diabeti c relatives, and 106 normal controls by PCR-RFLP assay. The body mass index (BM I), fasting insulin (FIns), fasting glucose (FPG), and lipid profile were also d etermined. Results The genotype and allele frequencies in DM g roup were the same as in control group. The systolic blood pressure(SBP), trigl ycerides(TG), total cholesterol (TC), and fasting plasma insulin of patients wit h QQ genotype were higher than those with KK genotype. The distribution of PC-1 genotypes and Q allele frequency in non-diabetic first-degree relatives wer e also similar to those in normal controls. The relatives carrying KQ genotype h ad the increased levels of diastolic blood pressure(DBP), triglycerides, total c holesterol, fasting and 2 h insulin, and fasting C peptide, although they had lo wer body mass index, as compared with those carrying KK genotype. In diabetic gr oup, only patients with hypertension had QQ genotype (2.38%). Concl usions There are no evident differences in the distribution of PC-1 ge notypes among T2DM, non-diabetic relatives, and normal controls. The K121Q geno types of PC-1 are associated with the features of IR in type 2 diabetic pedigre es. The K121Q polymorphism may have no contribution to the development of hypert ension in type 2 diabetes.