Insulin resistance (IR) is a characteristic of type 2 diabetes in which cells are unable to respond normally to insulin (a hormone produced when glucose is released into the bloodstream following the digestion of carbohydrates). Dietary fat intake is known to have a positive correlation with IR. However, researchers have yet to reach any conclusions regarding the extent to which interactions between genetics and the environment, specifically diet, may affect the established association between fat intake and IR.
A new study in the British Journal of Nutrition (2017) collected data from 622 twins (both monozygotic and dizygotic) between the ages of 7 and 15 in Jiaxing, Zhejiang Province (south-eastern China) in 2009. During the data collection process, mothers of the twins completed a questionnaire, giving details about family background and their children’s food consumption during the previous 12 months. Participants were weighed, measured, and interviewed by research staff. The children also provided a personal account of their regular diet using pictures of measuring plates and bowls to estimate portion sizes. Researchers measured fasting serum glucose and examined insulin to calculate insulin sensitivity in each participant.
By fitting the gene-diet interaction model, researchers comparatively analyzed the collected data to determine how diet and genetics affect insulin resistance (Homa-IR), glucose, and the Quantitative Insulin Sensitivity Check (QUICKI) index. Results showed that dietary fat intake significantly affected additive genetic effects on measures of particular type 2 diabetes traits, such as insulin, glucose, Homa-IR, and the QUICKI index. Researchers found evidence that correlations between fat intake and various type 2 diabetes traits are mediated by genetic factors.
The specific exclusion criteria for this study suggests that further investigation is required in order to draw broader comparisons for patients with type 2 diabetes who are not twins and are also outside of the age group and geographical location used in this study. However, being the first report of its kind to link estimates of gene-environment interactions to demonstrate how diet and genetics affect insulin resistance (IR), this study provides a key foundation for further research. It is important to note the ways in which environmental factors and genetic factors interact, particularly as it relates to our biology. Further examining this link will facilitate more in-depth patient education for those with type 2 diabetes to better understand how to modify their lifestyle and manage symptoms.
Written by Jennifer Newton