Physical Activity is Strongly Inversely Related To Post-Challenge Plasma Glucose and Glycemic Spikes in a Risk Population for Type 2 Diabetes

AIM: To examine the relationship between physical activity (PA) and various cardiometabolic risk factors during an oral glucose tolerance test (OGTT), including glycemic spikes (PGS) in individuals at risk for type 2 diabetes. SUBJECTS AND METHODS: A total of 949 middle-aged subjects from the Risk factors in Impaired Glucose Tolerance for Atherosclerosis and Diabetes (RIAD) trial aged 40-70 years were included in the present cross-sectional analysis. Standard 75 g OGTT was performed and blood was collected every 30 min for 2 hours for measurements of plasma glucose (PG) and other cardiometabolic risk factors. PA was assessed using interviewer-administered questionnaire. RESULTS: Post-challenge PGS and maximal PG (PGmax) during OGTT were significantly lower in individuals with high PA vs. individuals with low PA even after body mass index (BMI) adjustment (p = 0.026 and p = 0.035, respectively). In univariate analysis post-challenge PG 30, 60, 90, and 120 minutes, PGS and PGmax during OGTT were significantly inversely correlated to PA. This correlation was attenuated but remained significant after adjustment for BMI. Fasting PG and glycosylated hemoglobin were not correlated to PA. Significantly higher fasting and post-challenge insulin levels were found among subjects with low vs. subjects with medium (p < 0.05) and high PA (p < 0.05). Post-challenge C-peptide and proinsulin levels were significantly lower in participants with high vs. participants with low PA (p < 0.05 for all). The relationship between 2-h PG and PA was observed also in lean subjects and in subjects with normal fasting glucose. In multivariate analysis PA was a significant independent determinant of 2-h PG. CONCLUSION: We found a strong inverse relationship between PA and various post-challenge cardiometabolic parameters during OGTT, including glycemic spikes, in a population at risk for diabetes. This relationship was only partially dependent on BMI.