The Effect of Walking on Postprandial Glycemic Excursion in Patients With Type 1 Diabetes and Healthy People

OBJECTIVE

Physical activity (PA), even at low intensity, promotes health and improves hyperglycemia. However, the effect of low-intensity PA captured with accelerometery on glucose variability in healthy individuals and patients with type 1 diabetes has not been examined. Quantifying the effects of PA on glycemic variability would improve artificial endocrine pancreas (AEP) algorithms.

RESEARCH DESIGN AND METHODS

We studied 12 healthy control subjects (five males, 37.7 ± 13.7 years of age) and 12 patients with type 1 diabetes (five males, 37.4 ± 14.2 years of age) for 88 h. Participants performed PA approximating a threefold increase over their basal metabolic rate. PA was captured using a PA-monitoring system, and interstitial fluid glucose concentrations were captured with continuous glucose monitors. In random order, one meal per day was followed by inactivity, and the other meals were followed by walking. Glucose and PA data for a total of 216 meals were analyzed from 30 min prior to meal ingestion to 270 min postmeal.

RESULTS

In healthy subjects, the incremental glucose area under the curve was 4.5 mmol/L/270 min for meals followed by walking, whereas it was 9.6 mmol/L/270 min (P = 0.022) for meals followed by inactivity. The corresponding glucose excursions for those with type 1 diabetes were 7.5 mmol/L/270 min and 18.4 mmol/L/270 min, respectively (P < 0.001).

CONCLUSIONS

Walking significantly impacts postprandial glucose excursions in healthy populations and in those with type 1 diabetes. AEP algorithms incorporating PA may enhance tight glycemic control end points.Diabetes has reached epidemic proportions, especially in the U.S., and is classified mainly into type 1 and type 2 (1). Although type 2 diabetes constitutes ∼90% of the population burden of diabetes and is classically associated with a BMI that is >27 kg/m², modern society and improvements in multiple technologies have transformed type 1 diabetes into a disorder that is increasingly associated with obesity (2).Glycemic control remains a challenge in type 1 diabetes and is associated with extreme glucose variability of hypo- and hyperglycemia (3). An artificial endocrine pancreas (AEP) would represent a significant advance for patients with type 1 diabetes. Closed-loop algorithms for type 1 diabetes are currently being developed (4). Two major reasons for glucose excursions are food and physical activity (PA). How these factors interrelate, especially on an hour-to-hour basis and postprandially, is poorly documented. Incorporation of data from PA sensors into the AEP has the potential to improve the efficacy and safety of the system. Therefore, we examined the impact of levels of PA akin to activities of daily living on glycemic excursions.Low-cost motion sensors, such as accelerometers, exploit micro-electromechanical systems technology, making it possible to measure daily PA using miniature sensors worn underneath regular clothing. These accelerometers have been proven valid when compared with measurements of total daily energy expenditure performed using doubly labeled water (5). PA data thus captured along with the daily glucose profiles recorded by continuous glucose monitoring (CGM) sensors would enable us to better understand the underlying relationship.We studied healthy control subjects and patients with type 1 diabetes with the hypothesis that in patients with type 1 diabetes, glucose excursions are blunted by low-intensity PA.