BACKGROUND
Frequent and large fluctuations in blood glucose concentration during the day may increase risk of type 2 diabetes. It remains unclear how diet and physical activity affect glycemic variability in real-world conditions in persons without diabetes.
OBJECTIVE
We examined metabolic and lifestyle determinants (diet, physical activity, and sleep) of blood glucose levels over a seven-day period in people at high risk for diabetes
METHODS
Twenty-eight participants with a mean age of 46.0 (SD 9.9) years and a mean body mass index (BMI) of 27.5 (SD 1.8) kg/m2 underwent a mixed meal tolerance test to assess glucose homeostasis at baseline. Subsequently, they wore an accelerometer to assess movement behaviors, recorded their dietary intakes through a mobile phone application, and wore a flash glucose monitoring device that measured glucose levels every 15 min for seven days. Generalized estimating equation models were used to assess the associations of metabolic and lifestyle risk factors with daily mean glucose levels (mmol/L), the coefficient of variation (CV%) of glucose levels, and time-in-range (3.0 to 7.8 mmol/L, %).
RESULTS
A higher BMI (β = 0.12 per kg/m2; P = 0.01), body fat (β = 0.03 per kg; P = 0.01), and selected markers of hyperglycemia and insulin resistance from the meal tolerance test were associated with higher mean glucose levels during the seven days. Moderate-to-vigorous intensity physical activity (β = -1.77 per hr./d, P = 0.008) and polyunsaturated fat intake (β = -2.23 per 5 energy %, P < 0.001) were independently associated with less variation in glucose levels (CV%). Higher protein (β = 0.90, P = 0.007) and polyunsaturated fatty acid (β = 3.21, P = 0.02) intakes were associated with more time-in-range. In contrast, higher carbohydrates intake was associated with less time-in-range (β = -0.59, P = 0.04). Sleep, sedentary behavior, or light intensity physical activity were not independently associated with glucose measures.
CONCLUSIONS
Body fatness was associated with higher mean glucose levels, and moderate-to-vigorous intensity physical activity was associated with less glycemic variability throughout a week. Diets with higher protein and polyunsaturated fat, and lower carbohydrates were associated with more time in normal glucose range. Physical activity and dietary composition can substantially influence glucose variation in people at high risk of diabetes.