rs7923837

This case-control study investigated 25 T2DM-associated SNPs in a multi-ethnic Hawaiian cohort (291 GDM cases, 734 controls) and found ethnicity-specific associations with gestational diabetes. Key findings in Filipinos included rs1113132 (EXT2, OR=1.52, p=0.028), rs1111875 (HHEX, OR=1.5, p=0.047), rs2237892 (KCNQ1, OR=0.49, p<0.001), rs10830963 (MTNR1B, OR=0.63, p=0.025), and rs13266634 (SLC30A8, OR=0.58, p=0.011). In Japanese women, rs4402960 (IGFBP2, OR=0.5, p=0.031) and rs2237892 (KCNQ1, OR=0.5, p=0.03) were significant. Pacific Islanders showed associations with rs10830963 (MTNR1B, OR=0.52, p=0.037) and rs13266634 (SLC30A8, OR=2.43, p=0.03). No SNPs showed consistent associations across all three ethnic groups.

Association analysis of 31 GWAS-confirmed type 2 diabetes SNPs in 3,089 Indian sib pairs (2,528 for quantitative traits, 561 for diabetes) identified significant associations with intermediate traits: CDKAL1 rs7756992, TCF7L2 rs7903146 and rs12255372 with fasting glucose (β=0.009-0.01, p≤0.01); ADAM30 rs2641348, NOTCH2 rs10923931, TCF-2/HNF1B rs757210, and CDKN2A/B rs10811661 with fasting insulin and HOMA-IR (β=±0.05-0.09, p≤0.05); and THADA rs7578597 with type 2 diabetes (OR 1.5, p=0.03).

The HERITAGE Family Study examined eight type 2 diabetes susceptibility variants in 481 sedentary individuals undergoing 20-week endurance training. PPARG rs1801282 (Pro12Ala) was the only significant finding: Ala carriers showed greater improvements in glucose tolerance (p=0.0008), glucose effectiveness (p=0.004), and disposition index (p=0.003) in response to exercise training, though no associations were found with other recently identified GWAS variants.

This case-control study in 869 Korean women with gestational diabetes mellitus (GDM) and 632 non-diabetic controls examined whether type 2 diabetes-associated genetic variants discovered in recent GWAS are also associated with GDM. Multiple variants showed significant associations with GDM, including rs7756992 and rs7754840 in CDKAL1 (OR 1.55, p=4.17×10⁻⁹), rs10811661 in CDKN2A-CDKN2B (OR 1.49, p=1.05×10⁻⁷), variants in HHEX, rs4402960 in IGF2BP2 (OR 1.18, p=0.03), rs13266634 in SLC30A8 (OR 1.24, p=0.005), and rs7903146 in TCF7L2 (OR 1.58, p=0.038).

In 1,412 non-diabetic German participants, carriers of higher cumulative loads of type 2 diabetes risk alleles (rs7903146 in TCF7L2, rs7754840 in CDKAL1, rs7923837 in HHEX, rs13266634 in SLC30A8) showed significantly accelerated age-dependent decline in insulin secretion and impaired proinsulin conversion. Individuals with 5-8 risk alleles exhibited a ~13-18% reduction in insulin secretion compared to carriers of ≤3 alleles, with effects particularly pronounced in obese participants.

This candidate gene study of 1,065 German participants investigated seven type 2 diabetes-associated SNPs and their relationship with proinsulin processing. Risk alleles in TCF7L2 (rs7903146), CDKAL1 (rs7754840), and SLC30A8 (rs13266634) significantly impaired proinsulin to insulin conversion (p<0.05), while variants in HHEX showed impaired insulin secretion without affecting proinsulin conversion, demonstrating that these two aspects of beta cell dysfunction are independently regulated.

The D.E.S.I.R. prospective cohort study (N=4,707) validated 22 SNPs from genome-wide association studies for type 2 diabetes effects on glucose homeostasis. Risk alleles in SLC30A8 (rs13266634, P=0.0003), NGN3 (rs10823406, P=0.01), and MMP26 (rs2499953, P=0.04) were associated with elevated fasting glucose, while CDKAL1 variants (rs7756992, P=0.003) showed reduced fasting insulin. However, associations with type 2 diabetes incidence were modest (HRs ranging 1.25-2.03), and only SLC30A8 remained significant after Bonferroni correction for HOMA-B.

This case-control association study in 864 Japanese type 2 diabetes patients and 864 controls confirmed that three SNPs in HHEX (rs5015480 OR=1.46, rs7923837 OR=1.40, rs1111875 OR=1.30) were significantly associated with type 2 diabetes across ethnic groups. SNPs in FTO, CDKAL1, CDKN2B, and SLC30A8 showed nominal associations, while several SNPs were associated with impaired pancreatic beta cell function measured by HOMA-beta index.