The beneficial metabolic effects of time-restricted eating in adults with type 2 diabetes

A new study published in Diabetologia (the journal of the European Association for the Study of Diabetes [EASD]) finds that following a time-restricted eating (TRE) protocol which limits food intake to a max 10-hour time window shows promising beneficial metabolic effects in adults with type 2 diabetes (T2D).

Our modern 24-hour society is characterized by endless food availability and disrupted day-night rhythm brought on by irregular sleep-activity patterns and frequent exposure to artificial light sources. In Western nations, people also tend to spread their daily food intake over a minimum of 14 hours, which is likely to result in the absence of a true, nocturnal fast state. These factors all contribute to the development of T2D which has become one of the most common metabolic diseases globally, estimated by the World Health Organization to cause more than 1.5 million deaths per year.

The researchers recruited 14 individuals with T2D for the study, aged between 50 and 75 years (7 male, 7 female, average age 67.5 years) and with body mass index (BMI) ≥25 kg/m2. The study consisted of two 3-week intervention periods: TRE and control (CON), separated by a wash-out period of at least 4 weeks. At the start of each intervention, participants had their body weight measured and were fitted with a continuous glucose monitoring (CGM) device which measured their blood sugar level every 15 minutes. They were instructed to keep to their normal sleep patterns and physical activity and to maintain a stable weight. A food and sleep diary completed during the first intervention was used to ensure that diet during the second period was similar in both quantity and quality.

During TRE participants were instructed to consume their normal diet within a 10-hour window during the daytime, and to complete their food intake no later than 1800H. Outside this time window, they were permitted to drink water, plain tea, or black coffee, and zero-calorie soft drinks were also allowed during the evening if consumed in moderation. During CON volunteers were only required to spread their normal food intake over at least 14 hours, with no other restrictions.

TRE was found to decrease 24-hour glucose levels, primarily as a result of lower nocturnal blood sugar, and the average time spent with blood glucose in the normal range increased to 15.1 hours versus 12.2 hours during the CON phase. Morning fasting glucose was consistently lower among the TRE group than those on the control diet, which may be the result of lasting changes in nocturnal glucose control. Time spent in hypoglycemia (low blood sugar) was not significantly increased by TRE and no serious adverse effects were reported resulting from the protocol, demonstrating that an eating window of approximately 10 h is a safe and effective lifestyle intervention for adults with T2D.

Approximately halfway through each intervention, liver glycogen levels were assessed in the morning following the 10 h or 14 h night-time fast period and were measured again at the end of each study period after an 11 h fast for both TRE and CON. In both cases, liver glycogen did not differ significantly between TRE and CON, and analysis of liver fats showed no difference in their quantity or composition between interventions.

The authors concluded that "A daytime 10 h TRE regimen for 3 weeks decreases glucose levels and prolongs the time spent in the normal blood sugar range in adults with T2D as compared with spreading daily food intake over at least 14 h. These data highlight the potential benefit of TRE in T2D"

Ref: Andriessen, C., Fealy, C.E., 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 randomized crossover trial. Diabetologia (2022). https://doi.org/10.1007/s00125-022-05752-z