Exercise as it relates to Disease/Result of Exercise on Overnight Glycemic Control in Children with Type 1 Diabetes

This is an analysis of the journal article: "Impact of Exercise on Overnight Glycemic Control in Children with Type 1 Diabetes Mellitus".

What is the background to this research?
The research conducted in this article was specifically made to determine the affect that exercise had on young children when determining glycemic control in type 1 diabetes. It is widely known that physical exercise presents doctors, parents and patients with a dilemma. Exercise is highly encouraged in children, but for those affect by type 1 diabetes, exercise can make the regulation of blood glucose levels more difficult to measure during and after the period of exercise.

The possibility that prolonged periods of exercise during the day may increase the risk of severe hypoglycaemia during the night is a very common concern. A number of studies in children and adults have demonstrated that most severe hypoglycaemic events occur at night and suggests that such events are more frequent after days of increased physical activity.

Where is the research from?
This research article was part of the Journal of Paediatrics - October 2005, and was conducted by the Diabetes Research in Children Network Study Group. - "Impact of Exercise on Overnight Glycemic Control in Children with Type 1 Diabetes Mellitus" pg. 528 - 534

What kind of research was this?
The research conducted was a controlled study taking place at five clinical sites, containing 50 subjects with Type 1 Diabetes, all of which were aged between 11 and 17 years. The subjects were studied in a clinical research centre on two separate days.

One day included an afternoon exercise session on a treadmill, whereas the one day did not include any exercise. On both days, frequently sampled blood glucose levels were measured at the DirectNet central lab. - Insulin doses were similar on both days.

What did the research involve?
Study Procedures

The research conducted involved two inpatient stays in the CRCs (Cooperative Research Centre) at each of the DirectNet study sites. These stays lasted about 24 hours each and were separated by 1 to 4 weeks.

- Stay 1: 75 minutes exercise session in the late afternoon, known as the exercise day.

- Stay 2: No exercise needed, known as the sedentary day.

The order of the exercise day and sedentary days were determined at random.

The stays at the CRC included many different recordings of the subjects 'at home' behaviours. Before the first admission, the subject's daily meal plan and insulin algorithms used at home were recorded. Meals and bedtime snacks of similar caloric and carbohydrate content were consumed. Insulin management on both the exercise day and sedentary day were as similar as possible and followed the same routine that the subject would follow at home on a day without exercise.

Exercise Procedures

On the morning of the exercise day the subject walked on a treadmill for 5–15 minutes to determine the settings needed to achieve a heart rate of 140bpm. These settings were used for the start of the exercise session, which began at 4pm. The exercise session consisted of 15 minutes walking on a treadmill at a heart rate of 140bpm, followed by a 5 minute rest period. This cycle was repeated 3 more times, equalling 4 - 15 minute exercise periods.

Evening and Overnight Procedures

Each night, dinner was consumed at 6:15pm. After dinner, blood glucose levels were checked at 7:00pm, 8:00pm and 9:00pm. A bedtime snack was given at 9:30pm if the subject would normally receive one as part of their sedentary treatment regime. The subject was asked to sleep from 10:00pm and was woken at 7:00am. Blood glucose measurements were made using samples from a intravenous catheter every half-hour from 10:00pm through to 6:00am.

What were the basic results?
During exercise, plasma glucose levels fell in almost all subjects: 11 subjects (22%) developed hypoglycaemia.

Mean glucose levels from 10:00pm to 6L00am was lower on the exercise day that on the sedentary day: 131 vs 154 mg/dL; P = 0.003

Hypoglycaemia developed overnight more often on the exercise nights than on the sedentary nights: P = 0.009, occurring on the exercise night only in 13 (26%), on the sedentary night only in 3 (6%), on both nights in 11 (22%), and on neither night in 23 (46%). Hypoglycaemia was unusual on the sedentary night if the pre-bedtime snack glucose level was > 130 mg/dL.

How did the researchers interpret the results?
The results were interpreted via the change in blood glycemic levels over the course of a night, determined by the amount of physical activity that the participants undertook prior.

What conclusions should be taken away from this research?
The research demonstrated indicates that hyperglycaemia after exercise plays a direct correlation in overnight glycemic levels in children with type 1 diabetes. This results of this data supported the importance of modifying type 1 diabetes management after exercise, enabling the children to reduce their risk of overnight hypoglycaemia.

What are the implications of this research?
Allowing most children to maintain a consistent and healthy lifestyle via exercise allows them to keep down their blood glucose levels as they sleep each night. As stated in the research, afternoon exercise is able to reduce glycemic levels overnight. This also enables children to maintain a healthy body weight and reduce the risk of obesity. Due to this research, children now have the knowledge to start or continue exercise when affected with type 1 diabetes as it is beneficial for their overall health.