Intermittent fasting improves blood sugar control in adults with type 2 diabetes regardless of time of day

Restricting the eating window to eight hours a day – known as intermittent fasting – significantly improves blood sugar levels control in adults with type 2 diabetes no matter what time of day, according to new research. 

The study, which included both women and men, found that the benefits of fasting for 16 hours a day were evident in just three days, even without restricting calories or changing the types of food people ate. 

Previous studies have indicated that time-restricted eating – which limits when, but not what people eat – can improve the body’s ability to respond to insulin in people at risk of type 2 diabetes, but this has been attributed to reduced energy intake. 

This study, led by Dr Kelly Bowden Davies, Senior Lecturer Exercise Physiology at Manchester Metropolitan University, examined the impacts of changes in meal timing when participants were in energy balance which is where energy intake is matched with energy expenditure. 

The research involved 15 overweight, sedentary adults, nine female and six male, with an average age of 52, who habitually spread their eating period over more than 14 hours a day. They were assigned to two different eating patterns for three days at a time. 

“Our study found that restricting eating to a window of eight hours per day significantly improved the daily time spent in the normal blood glucose range and reduced fluctuations in blood glucose levels. However, altering the eight-hour restricted eating period to earlier or later in the day did not appear to offer additional benefits,” said Dr Bowden Davies. 

“Our findings, which can be attributed to the 16-hour fasting window rather than the time of eating or changes in energy intake, also highlight that the benefit of time-restricted eating can be seen within just three days.  

“Although time-restricted eating is becoming increasingly popular, no other studies have examined tightly controlled diet and altered the clock time of an eight-hour eating window on glycaemic control in people at risk of type 2 diabetes. 

“Many people find counting calories hard to stick to in the long term, but our study suggests that watching the clock may offer a simple way to improve blood sugar control in people at risk of type 2 diabetes, irrespective of when they have their eight-hour eating window, which warrants investigation in larger studies and over the longer term.” 

Dr Bowden Davies’ findings were presented at the European Association for the Study of Diabetes assembly in Madrid.