Understanding the role of integrated grip strength, physical activity, diet, and adiposity-related body composition in the development of type 2 diabetes: insights from the UK Biobank cohort

Boonpor, Jirapitcha (2025) Understanding the role of integrated grip strength, physical activity, diet, and adiposity-related body composition in the development of type 2 diabetes: insights from the UK Biobank cohort. PhD thesis, University of Glasgow.

Abstract

Type 2 diabetes (T2D) is a major contributor to cardiovascular disease risk and global mortality. T2D develops through complex biological pathways influenced by modifiable lifestyle behaviours and sociodemographic context. Accordingly, this thesis explores the relationship between traditional and emerging cardiometabolic risk factors, such as grip strength, physical activity (PA), dietary patterns, and obesity-related indicators, with the incidence of T2D.

This research uses data from the UK Biobank, a large-scale population-based prospective study encompassing over 500,000 participants from across the UK. Dietary exposures were self-reported, while PA was objectively quantified using wrist-worn accelerometers. Grip strength was assessed using a hand dynamometer, and obesity-related indicators were derived from anthropometric measurements taken by trained personnel. The incidence of T2D was obtained from primary care and hospital records. Cohort analyses were conducted using harmonised methods across exposures, including multivariable Cox regression, subgroup analysis, and mediation modelling.

The findings of this thesis reveal that lower absolute or relative (kg, or kg/body mass) grip strength is linked with an increased risk of developing T2D in both women and men, compared to those with normal grip strength. Notably, relative grip strength exhibits a more pronounced association with T2D risk than absolute grip strength (12% for men and 20% for women vs. 11% for men and 12% for women). Furthermore, low grip strength may serve as an early indicator of heightened T2D risk. In terms of PA, adherence to the WHO’s PA guidelines, as measured by accelerometers, is associated with a reduced risk of T2D (50%-70% depending on intensity and time spent). The magnitude of these associations is significantly greater than those reported in previous studies based on self-reported PA. Dietary analysis indicates that fish eaters (pesco-vegetarians) and those consuming fish and poultry have a lower risk of T2D (42% and 28%, respectively) compared to omnivores, while vegetarian diets show no significant association. This discrepancy may be due to a poor quality of diet, underreporting, or misclassification. Additionally, among 11 obesity-related markers evaluated for T2D risk prediction, 9 demonstrate an association, with the waist-to-height ratio (WHtR) showing the strongest predictive value, which could potentially benefit clinical screening practices. Sociodemographic factors, such as sex, age, and ethnicity, modified both exposure levels and T2D risk.

These findings offer new insights into the roles of both emerging and established risk factors for T2D, supporting the existence of a shared biological pathway in which poor diet, low muscle strength, and physical inactivity contribute to central adiposity, systemic inflammation, and muscle insulin resistance. These interrelated exposures act synergistically, often beyond what is captured by body mass index-based models, to drive the development of T2D.

Integrated prevention strategies should therefore address behavioural, physiological, and sociodemographic dimensions to effectively reduce the burden of T2D. Among the behavioural and phenotypical factors investigated, central adiposity, particularly WHtR, emerged as one of the strongest risk factors for T2D.

However, caution is warranted when interpreting these results due to the observational nature of the study, which limits causal inference. Future research should focus on clarifying the potential causal relationships underlying these associations.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Supported by funding from the Royal Thai Government Scholarship and Kasetsart University.
• Subjects: R Medicine > R Medicine (General); R Medicine > RC Internal medicine
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
• Funder's Name: Royal Thai Government Scholarship, Kasetsart University
• Supervisor's Name: Celis-Morales, Dr. Carlos, Gray, Professor Stuart R. and Ho, Dr. Frederick K.
• Date of Award: 2025
• Depositing User: Theses Team
• Unique ID: glathesis:2025-85638
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 04 Dec 2025 11:43
• Last Modified: 04 Dec 2025 15:10
• Thesis DOI: 10.5525/gla.thesis.85638
• URI: https://theses.gla.ac.uk/id/eprint/85638

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