Food consumption confined to a 10-hour period for adults with T2D led to increased time in range and lowered nocturnal and fasting glucose.
In adults with type 2 diabetes (T2D), time-restricted eating (TRE), ie, daily food consumption limited to a 10-hour window, resulted in improved glycemic time in range and 24-hour glucose homeostasis, suggesting that TRE may help support management of T2D, say authors of a new study published online July 25 in the journal Diabetolgia.
Modern 24-hour society fosters perfect conditions for development of T2D, including “ubiquitous” food availability and disrupted sleep activity, writes the study team from NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, the Netherlands, and led by Patrick Schrauwen, PhD.
Food intake in Western society, they add, is typically spread over a minimum of 14 hours which ostensibly cancels out a true nocturnal fasting state, a condition necessary to balance energy use. “Time-restricted eating is a novel strategy to improve metabolic health and has been proposed to counteract the detrimental effects of eating throughout the day by limiting food intake to daytime hours."
A prolonged overnight fast is expected to more effectively deplete hepatic glycogen stores and lead to improved insulin sensitivity. Schrauwen and colleagues cite previous research that found beneficial metabolic effects, (increased lipid oxidation, decreased plasma glucose levels, improved insulin sensitivity), with a 6–8-hour TRE program in overweight and otherwise healthy adults. They point out, however, that the short eating window and highly controlled study conditions in that study could limit applicability of the eating regimen in real life.
With that thought and the understanding that the effects of TRE on metabolic outcomes in adults with T2D are unclear, Schrauwen and colleagues aimed specifically to examine how TRE during a “feasible” 10-hour period followed for 3 weeks in real life conditions would impact hepatic glycogen levels and insulin sensitivity in a T2D population.
The investigators enrolled 14 participants (7 men, 7 women) with T2D for the randomized crossover study. The cohort’s average age was 67.5 years and body mass index was ≥25 kg/m2. Participants were randomly assigned to a TRE intervention for which all food for each day was to be consumed over a 10-hour period that concluded no later than 6 pm or to a control intervention in which the day’s food intake was consumed over 14 hours with no other restrictions.
After 3 weeks following the first intervention, participants went through a 4-week washout period, after which they crossed over to the opposite intervention.
Researchers weighed participants at the start of each intervention and fitted them with a continuous glucose monitor (CGM). They were instructed to maintain their normal dietary habits, physical activity, and sleep patterns and to not gain/lose weight. They kept a food and sleep diary in order to match behavior in the crossover intervention.
The investigators report that based on analysis of CGM data, mean 24-hour glucose levels were lower during the TRE period compared the control period (6.8 mmol/L vs 7.6 mmol/L; P <.01), a result they suggest is likely related to the consistently lower nocturnal glucose levels seen with the TRE vs control intervention, a finding supporting their hypothesis that restoring balance between fed/fasted states could enhance metabolic health.
Similarly, morning fasting glucose was consistently lower during TRE than during control, which may also be a result of durable changes in overnight glucose control.
Importantly the number of hours spent in normoglycemia increased during during TRE compared with control conditions (15.1±0.8 vs 12.2±1.1 h/day, p=.01).
In tandem, the team reports, time spent in the high glucose range (7.3–9.9 mmol/l) was less in TRE compared with control (5.5±0.5 vs 7.5 0.7 h/day, respectively, p=.02). Nor did TRE increase time spent in hyperglycemia vs control eating (2.3±0.4 vs 3.7±0.8 h/day, p=0.24), time spent in the low glucose range (0.5±0.1 vs 0.4±0.1 h/day, p=1.00) nor time spent in hypoglycemia (0.7±0.3 vs 0.1±0.0 h/day, p=0.48).
They found, also, that while energy expenditure during a 24-hour period was not impacted, TRE was associated with a decrease in 24-hour glucose oxidation (260.2±7.6 vs 277.8±10.7 grams/day; P=.04)
Schrauwen et al found that unlike previous TRE research in adults with overweight/obesity, the current protocol did not impact insulin sensitivity; they speculate that the much shorter eating window of 6 hours that closed at 3 pm, thus extending the period of fasting, may be responsible for the difference in findings. They add, however, that the previous study's design also was not compatible with the average lifestyle of an adult with T2D and that additional research on duration of fasting will be crucial to determining impact on insulin sensitivity.
Morning hepatic glycogen levels were assessed halfway through each intervention but, as with insulin senstivity, there were no significant differences found between the TRE and control sessions nor did analysis of hepatic fat reveal differences in quantity or composition between the interventions.
“Despite the lack of changes in hepatic glycogen and insulin sensitivity, we did find that our 10-hour time-restricted eating protocol decreased 24-hour glucose levels in individuals with type 2 diabetes, primarily driven by decreased nocturnal glucose levels,” wrote investigators. “Notably, time-restricted eating also lowered overnight fasting glucose, increased the time spent in the normal glucose range and decreased time spent in the high glucose range, all of which are clinically relevant variables in type 2 diabetes.”
They conclude, “Since our TRE protocol was feasible and safe, and resulted in improved 24 h glucose levels, it would be interesting to examine the impact of 10 h TRE on glucose regulation and insulin sensitivity in type 2 diabetes in the long term to address the clinical relevance of TRE.”
Reference: Andriessen C, Fealy CE, Veelen A, et al. Three weeks of time-restricted eating improves glucose homeostasis in adults with type 2 diabetes but does not improve insulin sensitivity: a randomised crossover trial. Diabetologia. Published online July 25, 2022. doi:10.1007/s00125-022-05752-z