Dietary Intake and TCF7L2 rs7903146 T Allele Are Associated with Elevated Blood Glucose Levels in Healthy Individuals
<b><i>Introduction:</i></b> Type 2 diabetes (T2D) is a leading cause of global mortality with diet and genetics being considered amongst the most significant risk factors. Recently, studies have identified a single polymorphism of the <i>TCF7L2</i> gene (rs7903146) as the most important genetic contributor. However, no studies have explored this factor in a healthy population and using glycated haemoglobin (HbA1c), which is a reliable long-term indicator of glucose management. This study investigates the association of the genetic polymorphism rs7903146 and dietary intake with T2D risk in a population free of metabolic disease. <b><i>Methods:</i></b> T2D risk was assessed using HbA1c plasma concentrations and dietary intake via a validated Food Frequency Questionnaire in 70 healthy participants. <b><i>Results:</i></b> T allele carriers had higher HbA1c levels than the CC group (32.4 ± 7.2 mmol/mol vs. 30.3 ± 7.6 mmol/mol, <i>p</i> = 0.005). Multiple regression reported associations between diet, genotype and HbA1c levels accounting for 37.1% of the variance in HbA1c (adj. <i>R</i><sup>2</sup> = 0.371, <i>p</i> < 0.001). The following macronutrients, expressed as a median percentage of total energy intake (TEI) in the risk group, were positively associated with HbA1c concentration: carbohydrate (≥39% TEI, <i>p</i> < 0.005; 95% CI 0.030/0.130) protein (≥21% TEI, <i>p</i> < 0.005, 95% CI 0.034/0.141), monounsaturated (≥15% TEI <i>p</i> < 0.05, 95% CI 0.006/0.163) and saturated fatty acids (≥13% TEI; <i>p</i> < 0.05, 95% CI 0.036/0.188). <b><i>Conclusion:</i></b> Carriers of the T allele showed significantly higher levels of HbA1c compared to non-carriers. Dietary intake affected T2D risk to a greater extent than genetic effects of <i>TCF7L2</i>rs7903146 genotype in a healthy population. The study focus on healthy individuals is beneficial due to the applicability of findings for T2D screening.