We assessed associations of GDM related genetic variants in/near the CDKAL1 (rs7754840) and MTNR1B (rs10830962) genes with changes in fasting levels of glucose and insulin, β-cell function (HOMA-B) and insulin resistance (HOMA-IR) at 1 year and 2 years after the baseline.
The most important risk alleles associated with GDM were rs10830963/G of MTNR1B (OR = 1.84/1.64 [IADPSG/m'99WHO], p = 0.0007/0.006), rs7754840/C (OR = 1.51/NS, p = 0.016) of CDKAL1 and rs1799884/T (OR = 1.4/1.56, p = 0.04/0.006) of GCK.
The minor alleles of rs7903146 (TCF7L2), rs12255372 (TCF7L2), rs1799884 (-30G/A, GCK), rs5219 (E23K, KCNJ11), rs7754840 (CDKAL1), rs4402960 (IGF2BP2), rs10830963 (MTNR1B), rs1387153 (MTNR1B) and rs1801278 (Gly972Arg, IRS1) were significantly associated with a higher risk of GDM.
These polymorphisms were in or near the following genes: TCF7L2 (rs7903146), MTNR1B (rs10830963), IGF2BP2 (rs4402960), KCNJ11 (rs5219), CDKAL1 (rs7754840), KCNQ1 (rs2237892 and rs2237895) and GCK (rs4607517); while no association was found for PPARG with GDM risk.
Two loci known to be associated with type 2 diabetes had a genome-wide significant association with GDM in the joint analysis. rs7754840, a variant in CDKAL1, had the strongest association with GDM (odds ratio 1.518; P=6.65×10(-16)).
We also found that the risk alleles of rs2383208 (b = -0.085, p = 0.003), rs4402960 (b = -0.057, p = 0.046) and rs10830963 (b = -0.096, p = 0.001) were associated with HOMA-B, while rs7754840 was associated with decrease in insulin AUC during a 100 g OGTT given at the time of GDM diagnosis (b = -0.080, p = 0.007).
Compared with controls (men and women combined), GDM</span> was associated with rs7756992 and rs7754840 (OR 1.55, 95% CI 1.34-1.79, p = 4.17 x 10(-9)) in CDKAL1; rs10811661 (OR 1.49, 95% CI 1.29-1.72, p = 1.05 x 10(-7)) in the CDKN2A-CDKN2B region; rs1111875 (OR 1.27, 95% CI 1.09-1.49, p = 0.003), rs5015480, and rs7923837 in HHEX; rs4402960 (OR 1.18, 95% CI 1.01-1.38, p = 0.03) in IGF2BP2; rs13266634 (OR 1.24, 95% CI 1.07-1.43, p = 0.005) in SLC30A8; and rs7903146 (OR 1.58, 95% CI 1.03-2.43, p = 0.038) in TCF7L2.