Haptoglobin Phenotype and Gestational Diabetes

OBJECTIVE—Haptoglobin (Hp), an Hb-binding plasma protein, exists in two major allelic variants. Hp1 has higher Hb binding and antioxidant capacity compared with Hp2. Individuals with Hp1 exhibit a lower incidence of angiopathies. Gestational diabetes mellitus (GDM) is an early manifestation of type 2 diabetes in pregnant women. It is usually confined to the time of gestation, but carries an increased risk to develop type 2 diabetes later in life. RESEARCH DESIGN AND METHODS—From consecutive Caucasian pregnant women (n = 250) referred for oral glucose tolerance testing, the Hp phenotype was determined. Significance of distribution and odds ratios (ORs) associated with Hp phenotype were calculated for women with GDM (n = 110) and women with normal glucose tolerance (n = 140). RESULTS—Frequency of GDM in Hp phenotype classes increased with the number of Hp2 alleles (P < 0.001). ORs for GDM in women heterozygous and homozygous for Hp2 were 2.7 (95% CI 1.06–6.84) and 4.2 (1.67–10.55), respectively. CONCLUSIONS—Hp phenotype is an apparent risk factor for the development of GDM in our study population. This might be due to the low antioxidative potential of Hp2 compared with Hp1.