Association of genetic variants related to plasma fatty acids with type 2 diabetes mellitus and glycaemic traits: a Mendelian randomisation study

Diabetologia. 2020 Jan;63(1):116-123. doi: 10.1007/s00125-019-05019-0. Epub 2019 Nov 5.

Abstract

Aims/hypothesis: Epidemiological data on the associations of circulating fatty acid levels with type 2 diabetes are inconsistent. We conducted a two-sample Mendelian randomisation study to explore the causal associations of plasma levels of ten fatty acids with type 2 diabetes and glycaemic traits.

Methods: Thirteen SNPs associated with circulating levels of ten individual fatty acids at the genome-wide significance level (p < 5 × 10-8) were selected as instrumental variables for the exposures. For the outcomes, summary-level data were obtained from the DIAbetes Genetics Replication And Meta-analysis (DIAGRAM) consortium for type 2 diabetes (898,130 individuals) and from the Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC) for the glycaemic traits (up to 46,186 non-diabetic individuals). The inverse-variance weighted method was used for analyses.

Results: Genetic predisposition to higher plasma levels of eight of the ten fatty acids were statistically significantly associated with lower or higher odds of type 2 diabetes. The OR per one SD increment of each fatty acid was 0.93 (95% CI 0.90, 0.96; p = 2.21 × 10-5) for α-linolenic acid, 0.96 (95% CI 0.94, 0.98; p = 1.85 × 10-4) for linoleic acid, 0.86 (95% CI 0.81, 0.91; p = 6.68 × 10-7) for palmitoleic acid, 0.87 (95% CI 0.81, 0.93; p = 2.21 × 10-5) for oleic acid, 1.08 (95% CI 1.03, 1.12; p = 0.002) for eicosapentaenoic acid, 1.04 (95% CI 1.02, 1.07; p = 0.001) for docosapentaenoic acid, 1.03 (95% CI 1.02, 1.05; p = 2.51 × 10-5) for arachidonic acid and 1.09 (95% CI 1.03, 1.15; p = 0.003) for stearic acid. The same eight fatty acids were also associated with fasting glucose levels and HOMA-B. The associations, except that for palmitoleic acid, were driven by variants in FADS1/2.

Conclusions/interpretation: Genetic predisposition to higher circulating levels of eight out of ten fatty acids was associated with type 2 diabetes, fasting glucose and islet beta cell function. However, the associations, except that for palmitoleic acid, were driven by variants in FADS1/2, which encode enzymes with a key role in fatty acid metabolism.

Keywords: Fatty acids; Genetic variants; Glycaemic traits; Mendelian randomisation; Type 2 diabetes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blood Glucose / metabolism
  • Diabetes Mellitus, Type 2 / blood
  • Diabetes Mellitus, Type 2 / genetics*
  • Fatty Acids / blood
  • Genetic Predisposition to Disease / genetics
  • Genome-Wide Association Study
  • Genotype
  • Humans
  • Mendelian Randomization Analysis
  • Phenotype
  • Polymorphism, Single Nucleotide / genetics

Substances

  • Blood Glucose
  • Fatty Acids