Abstract
Globally, the prevalence of type 1 diabetes mellitus (T1DM) is rising. In 2024, approximately 141,000 Australians had T1DM. Maintaining optimal glycaemic control of glycated haemoglobin A1c (HbA1c) ≤ 7.0% on a standard carbohydrate diet can be a challenge for people living with T1DM. The Diabetes Control and Complications Trial established that macrovascular and microvascular complications could be reduced by improving glycaemic control. Some recent studies indicate that a very low or low-carbohydrate diet (LCD) may improve glycaemic control. However, the overall evidence relating to an association between a very low or LCD and glycaemic control in people living with T1DM is both limited and mixed. Additionally, previous research has suggested that a reduced quality of life (QoL) because of anxiety and depression adversely influences glycaemic control. Despite some evidence suggesting a potential link between a very low or LCD and optimal glycaemic control, there is a lack of research specifically examining the relationship between LCDs, QoL, and glycaemic control, making this study unique in its approach.Aim
This doctoral study aimed to review the current literature and subsequently design and implement a study protocol to investigate the association between an LCD, QoL, and glycaemic control. As part of this research, a new T1DM-specific QoL questionnaire was developed and validated, and a clinical trial of an LCD was conducted involving Australian adults living with T1DM.
Methods
This doctoral research was underpinned by a pragmatic paradigm. To achieve the research aims, an exploratory sequential mixed methods design was employed, comprising four key phases:
Phase 1: To review the literature review.
Phase 2: To design a study protocol.
Phase 3: To develop and validate a new T1DM-specific QoL questionnaire.
Phase 4: To investigate whether an LCD mediates association between QoL and glycaemic control in adults with T1DM, pre and post a 12-week dietary intervention.
Results
The key finding of this research was that a 12-week LCD intervention (< 100 g/day) improved glycaemic control—as evidenced by a reduction in HbA1c—without compromising QoL among adults living with T1DM. Motivation and perceived health benefits emerged as enablers of adherence to an LCD. Conversely, barriers included the practical challenges of the diet, such as social occasions and holidays as well as limited access to LCD information, both of which negatively influenced adherence. Furthermore, this doctoral study developed and validated a QoL questionnaire for adults living with T1DM. The findings revealed that psychological and social domains significantly influenced QoL, with dietary wellbeing closely interwoven with psychological aspects such as ‘coping and adjusting’, ‘fear and worry’, and ‘loss and grief’. The significance of these findings is supported by the publication of four peer-reviewed manuscripts.
Conclusions
This doctoral research provides valuable insights into the association between LCD, QoL, and glycaemic control in adults living with T1DM. The findings suggest that an LCD may improve glycaemic outcomes without negatively impacting QoL. Additionally, the research highlights the role of psychological and social influences on dietary adherence and QoL. Together, these contributions help address an important gap in the literature and advance both clinical and psychosocial understanding of T1DM management. They also provide a foundation for future clinical and self-management strategies in T1DM.
| Date of Award | 2025 |
|---|---|
| Original language | English |
| Supervisor | Cathy KNIGHT-AGARWAL (Supervisor) & Rati JANI (Supervisor) |