The Genetic Effects of rs7903146 and Dietary Intake on Type 2 Diabetes Mellitus Risk in a Healthy Population

Study Overview
=================
Brief Summary
-----------------
This study investigates the association of genetic effects of rs7903146 and dietary intake on type 2 Diabetes Mellitus (T2DM) risk in a healthy population. T2DM risk was assessed through glycated haemoglobin (HbA1c) concentration in 73 subjects. Dietary intake was assessed using a validated food frequency questionnaire (FFQ).

Detailed Description
-----------------
Type 2 diabetes mellitus (T2DM) is a global epidemic linked to 1.6 million deaths in 2016. Diet, lifestyle and environment contribute significantly to T2DM-risk. Genome-wide association studies identify the transcription factor 7-like 2 (TCF7L2) rs7903146 (C/T) gene as one of the most important associated with T2DM-risk. The T-allele is associated with a two-fold increase in relative risk of T2DM across different populations. However, most studies associating genetic effects of dietary intake on rs7903146 and T2DM-risk utilised volatile instantaneous measures of glucose(5) and focussed on individual macronutrients. Understanding the association of rs7903146 and overall macronutrient intake using a stable blood homeostasis marker may provide a fuller insight into T2DM-risk. The study included data for all variables (participant characteristics: sex (female/male), age (years), height (cm), weight (kg), body mass index (BMI) (kg/m2), body fat percentage (%), fat mass (kg), lean mass (kg), waist/hip (ratio), dietary intake, HbA1c (mmol/mol and %) and physical activity (hours/week). All data was collected at St Mary's University between April to July 2019. Participants was genotyped and allocated into two groups: major allele (C) homozygote versus minor allele (T) homozygote plus heterozygote. T2DM-risk was assessed through their value of HbA1c and participants were classified as follows: normal (<42mmol/mol/ <6.0%), pre-diabetic (42 to 47 mmol/mol/ 6.0% to 6.4%), diabetes (48mmol/mol /6.5% or over).

Official Title
-----------------
The Association Between TCF7L2 rs7903146, Diet and Type 2 Diabetes Mellitus Risk

Conditions
-----------------
Health Behavior, Blood Glucose, High, Diet Habit, Genetic Predisposition

Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion criteria: Eligibility criteria required healthy adults free from metabolic condition and free from medication affecting glycated haemoglobin levels. Exclusion criteria: Individuals with HbA1c levels ≥48 mmol/mol or ≥6.5% were excluded due to a classification as T2DM (WHO, 2011).

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 64 Years

Sexes Eligible for Study
-----------------
All

Study Plan
=================
How is the study designed?
-----------------
What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| DNA | salivary (1-ml) DNA for genotype TCF7L2 gene (rs7903146 SNP) | 3 months | 
| Hba1c | capillary blood collected (via the ears or fingers) using a Microvette CB Lithium Heparin tube (SARSTEDT AG & C0., Nümbrecht, Germany) | 3 months | 
| Diet intake | Dietary intake estimated using The European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk (food frequency questionnaire) | 3 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Body weight | Body weight in kg measured by bioelectrical impedance analysis using a 0.5kg clothing offset | 3 months | 
| Waist | Waist measurement was taken midway between iliac crest and lowest rib | 3 months | 
| Hip | Hip circumference was measured over the greater trochanters at their widest point (nearest 0.1cm) | 3 months | 
| Height | Subject height was recorded to the nearest 0.1-cm via stadiometer | 3 months | 
| Physical activity | Assessed through Physical Activity Readiness Questionnaire (PAR-Q) | 3 months | 
| Fat mass | Measured in kg and percentage (%) measured by bioelectrical impedance analysis | 3 months | 
| Lean mass | Measured in kg and percentage (%) measured by bioelectrical impedance analysis | 3 months |