TABLE 2

Genetic studies of IL6 and IL6R in type 2 diabetes and insulin resistance

AssociationPopulation (ref. no.)GeneSNPAssociated allele/ genotypeCommentPower*
Type 2 diabetesNative Americans (22)IL6−174G>CG/GGPimas are GG heterozygous1
Type 2 diabetesSpanish Caucasians (22)IL6−174G>CG/GG1
Type 2 diabetesU.K. Caucasians (23)IL6−174G>CGOnly males included3
Type 2 diabetesGermans (19)IL6−174G>CGAssociation only significant in males and lean subjects2
Type 2 diabetesIL6−597G>AG2
Type 2 diabetesDanes (24)IL6−174G>CNone3
Type 2 diabetesIL6−572G>CGGSNP not in Hardy-Weinberg equilibrium in control group3
Type 2 diabetesIL6−597G>ANone3
Type 2 diabetesIL6HaplotypeGCG AGC/GCGHaplotype of −597, −572, and −174 SNPs, trend (P = 0.06) of association for GCG3
Conversion from impaired glucose tolerance to type 2 diabetesFinns (25)IL6−174G>CCCOnly in combination with TNFA-308 A allele carriers2
Prospective risk of developing type 2 diabetesGermans (26)IL6−174G>CCCIn individuals with BMI >28 kg/m22
Type 2 diabetesPimas (27)IL6Rrs8192284None1
Type 2 diabetesUtah Caucasians (11)IL6Rrs8192284Asp358Trend (P = 0.053)1
Type 2 diabetesAfrican Americans (11)IL6Rrs8192284None1
Type 2 diabetesDanes (12)IL6Rrs8192284Asp3583
Type 2 diabetesAfrican Americans (11)IL6Rrs2229238385Ile
High insulin sensitivityCatalonians (28)IL6−174G>CCC1
Low insulin sensitivityFinns (29)IL6−174G>CCC3
Low insulin sensitivityGermans (19)IL6−174G>CNone2
Low insulin sensitivityDanes (24)IL6−174G>CG3
  • *

    * The reports were ranked based on the number of investigated individuals and thus the power of the study: 1 = low, 2 = intermediate, or 3 = high power. Only studies evaluating insulin resistance using minimal model measures or the euglycemic-hyperinsulinemic clamp were included, since studies using less precise determinations of insulin resistance may be flawed. Studies investigating obesity alone contain no comments. Not all genetic variants investigated are commented on if considered noninformative in the context or no association was established.