Eating and fasting windows, late last meal timing, hours of night sleep, late bedtime onset, and poorer sleep quality are significantly associated with T2DM risk among FTO rs9939609 risk carriers and may reflect metabolic vulnerability associated with FTO risk alleles.
Longer eating windows were associated with increased risk for Type 2 diabetes under the additive genetic model.
Later last meal timing was associated with increased risk for Type 2 diabetes under the additive genetic model.
Longer fasting windows were found to be protective against Type 2 diabetes under the additive genetic model.
Later bedtime onset was associated with increased risk for Type 2 diabetes under the additive genetic model.
FTO rs9939609 risk allele carriers with prolonged sleeping windows had significantly increased risk of Type 2 diabetes.
FTO rs9939609 risk allele carriers with poorer sleeping quality had significantly increased risk of Type 2 diabetes.
Significant interactions were demonstrated between FTO rs9939609 and both eating and sleeping window variables in relation to T2DM risk.
This research suggests that people who carry a common genetic variant in the FTO gene (called rs9939609) may be especially vulnerable to developing Type 2 diabetes when they also have certain eating and sleeping habits. Specifically, eating over a longer stretch of the day, having a late last meal, going to bed late, sleeping for longer hours, and having poor sleep quality were all linked to higher Type 2 diabetes risk — and several of these factors had a stronger negative impact in people who carried the FTO risk variant. On the flip side, having a longer overnight fasting window (eating within a narrower daily window) appeared to be protective. The study was large, involving over 12,000 adults, and accounted for factors like age, sex, and body weight. This research suggests that genetic predisposition to Type 2 diabetes is not fixed — it can be amplified or potentially reduced by everyday behaviors like when you eat and when you sleep. For people who carry the FTO risk variant, the combination of irregular or late eating patterns and poor sleep may create a kind of 'metabolic double jeopardy' that substantially elevates their diabetes risk compared to non-carriers with the same habits. The practical implication highlighted by the authors is that behavioral modifications — such as aligning meals earlier in the day, maintaining a consistent and earlier bedtime, and improving sleep quality — could represent actionable strategies to reduce Type 2 diabetes risk, particularly for individuals who are genetically predisposed. Because the study is cross-sectional (a snapshot in time rather than following people over years), it cannot prove that these habits directly cause diabetes, but the findings provide a basis for further research into personalized, genetics-informed lifestyle interventions.
Kazarnovsky Nahshan L, Chermon D, Birk R. (2026). The Common FTO rs9939609 Polymorphism Interacts with Sleeping and Eating Windows to Affect Predisposition to Type 2 Diabetes.. Nutrients. https://doi.org/10.3390/nu18030472