TRIB3 R84 variant affects glucose homeostasis by altering the interplay between insulin sensitivity and secretion

Area of Science:

• Genetics
• Metabolic Disorders
• Human Physiology

Background:

• Replication of genetic association studies is crucial for establishing findings.
• The TRIB3 Q84R polymorphism (rs2295490) has been previously linked to glucose homeostasis.
• Understanding genetic influences on complex traits requires robust statistical validation.

Purpose of the Study:

• To replicate the association between the TRIB3 Q84R polymorphism and glucose homeostasis.
• To investigate the impact of the TRIB3 R84 variant on impaired glucose regulation (IGR).
• To examine the relationship between TRIB3 R84, insulin sensitivity (ISI), and insulin secretion (disposition index [DI]).

Main Methods:

• Studied three European cohorts (total n=1561) with fasting glucose <7.0 mmol/l.
• Genotyped the TRIB3 Q84R polymorphism using TaqMan allele discrimination.
• Assessed impaired glucose regulation (IGR), insulin sensitivity (ISI), and disposition index (DI) via oral glucose tolerance tests and glucose clamps.

Main Results:

• R84 carriers showed a significantly higher risk of IGR (OR 1.54-1.63, p<0.05).
• Individuals with the R84 variant exhibited progressively lower insulin sensitivity and disposition index.
• The association with IGR was primarily mediated by altered disposition index, not solely insulin sensitivity.

Conclusions:

• The TRIB3 R84 variant significantly impacts glucose homeostasis in Europeans.
• The genetic effect on glucose regulation is mediated by impaired interplay between insulin secretion and sensitivity.
• These findings confirm the role of TRIB3 R84 in metabolic regulation.