Background: Type 2 diabetes (T2DM) is a major cause of morbidity and mortality in the United Kingdom (UK) and measures to mitigate risk have been largely ineffective in reducing incidence. Time-restricted eating (TRE) (energy intake typically restricted to ≤12 hours/day) improves markers of metabolic health but its application in T2DM is poorly studied. A particular need is to understand whether to place the daily eating window early or late in the day.

Methods: A cross-sectional questionnaire (Study 1) explored changes in eating behaviours, including temporal eating patterns, in UK workers during the Covid-19 pandemic. Study 2 investigated the effects of a 10-week TRE protocol on appetite, food preferences and social interactions in adults at increased risk of developing T2DM. Study 3 investigated acute glycaemic effects of early- versus late-TRE in adults with T2DM during a 9-day, 3-arm cross-over dietary intervention protocol.

Results: Habitual TRE was reported by >25% of respondents (n = 44/166) in Study 1. No difference in weight management was observed between those following TRE and those not. In Study 2, TRE negatively impacted the social interactions of all participants (n = 8) and significantly increased subjective hunger (p = 0.021) and appetite (p = 0.018) before first meal, and before bed (hunger, p = 0.015; appetite, p = 0.003). However, TRE was well-tolerated and revealed a preference for late-TRE compared to early-TRE. Study 3 revealed that late-TRE significantly reduced indices of glycaemic variability (CV and SD, p<0.001), reduced 3-hour postprandial responses (p = 0.026) and increased glucose time in range (p = 0.026) compared to early-TRE and non-TRE.

Conclusions: Contrary to previous research of early-TRE in healthy populations, these data suggest that short-term late-TRE exerts superior glycaemic benefits in individuals with T2DM. As Study 1 did not show a clear effect of TRE on body weight and given the preference for late-TRE in Study 2, and short duration of the TRE intervention in Study 3, a long-term study of early- versus late-TRE in T2DM patients, is warranted.