Participation in 12 weeks of the Saskatchewan Health Authority’s Diabetes Wellness Series: Effects on appetite hormone response to a mixed meal tolerance test

Abstract

Food intake (FI) dysregulation in type 2 diabetes (T2D) may be due to impaired tonic satiety signals (e.g., insulin, leptin) and episodic FI signals (e.g., glucose, acyl-ghrelin [a-ghrelin; appetite-stimulating], active glucagon-like peptide-1 [aGLP-1; appetite-inhibiting]), promoting caloric overconsumption. Research has shown that regular physical activity is associated with more sensitive appetite control. The present thesis aimed to: (1) investigate the acute responsiveness of FI regulatory signals (glucose, insulin, a-ghrelin, aGLP-1) and perception of appetite to a 120-minute mixed meal tolerance test (MMTT) in individuals with T2D, and (2) assess the impact of participation in 12 weeks of the Saskatchewan Health Authority’s (SHA) Diabetes Wellness Series (DWS) program, incorporating exercise (aerobic and resistance) and education (e.g., nutrition, mental health, stress, etc.), on FI regulatory signal responsiveness and perception of appetite to an MMTT. Data from 21 participants (9M, 12F; age = 68.0±9.8 y; duration of T2D diagnosis = 11.0±10.7 y) was collected for Objective 1; values for blood glucose (6.4±1.7, 7.5±2.2, 8.8±2.2, 9.5±2.6, 9.6±3.1, 8.4±3.0mmol/L), a-ghrelin (251.9±198.5, 189.3±147.5, 151.1±124.7, 159.1±147.7, 129.3±113.2, 213.4±193.5pg/ml), aGLP-1(1.1±1.1, 3.0±2.6, 3.4±4.0, 1.8±1.6, 1.7±2.5, 1.5±1.3 pM), insulin (19.3±9.1, 28.5±19.4, 40.7±31.9, 56.6±40.9, 47.9±33.2, 36.9±28.6 ulU/mL), and average appetite (AA; via visual analog scale) (47.7±22.2, 38.6±23.2, 38.7±19.2, 36.1±17.1, 46.4±20.0, 51.5±16.7 mm) were observed before, and at 15, 30, 60, 90, and 120-mintute after consuming a 237g Boost® (240kcal [56.4% carbohydrate, 24.9% protein, and 18.7% fat]). Repeated measures General Linear Model (GLM) analyses revealed a significant effect of time for all FI regulatory signals and perception of appetite (p<0.05). Compared to the literature on metabolically healthy adults, fasted values of a-ghrelin were low while fasted values of glucose, insulin, leptin, and aGLP-1 were high, and there was an impaired responsiveness to the MMTT. No relationship between FI regulatory signals and AA suggests a disrupted association between FI signals and perception of appetite in T2D. Sixteen participants (7M, 9F; age = 69.0±11.0 y; duration of T2D diagnosis = 11.0±10.3 y) returned after the 12-weeks of SHA DWS programming. Factorial repeated GLM analyses assessed main effects of training state (pre vs. post) and time (0, 15, 30, 60, 90, 120 minutes) and their interactions; no interactions or main effects of training-state were found; however, a main effect of time was observed for all FI regulatory signals and perception of appetite (p<0.05). Incremental area under the curve (iAUC) analyses showed increased aGLP-1 (p=0.03) and a trend towards decreased a-ghrelin (p=0.07). The hormone ‘sensitivity’ did not change at post-intervention; however, no significant change in the relationships between FI regulatory signals and AA were observed. While 12 weeks of adherence to the SHA DWS had a positive influence on some aspects of FI regulation, it may not have been enough to elicit clinically significant changes. The DWS should continue to be promoted to expose individuals with T2D to exercise programming and education; however, extending the program duration beyond 12 weeks to allow more time for habit formation (i.e., positive lifestyle change), introducing more intensive and frequent exercise sessions, and adopting a more focused approach to nutrition and dietary changes may be necessary to enhance the effectiveness of the DWS. Further, future directions to address the high incidence and prevalence of T2D in Saskatchewan should include prevention in addition to management.