To examine the effectiveness of a group-based lifestyle modification program followed by peer-led telephone counselling for type 2 diabetes (T2D) and cardiovascular disease risk reduction. The lifestyle modification program will support daily ambulatory activity and low glycemic index food intake among women with previous gestational diabetes mellitus (GDM).

Study Objective:

To examine the effectiveness of a group-based lifestyle modification program followed by peer-led telephone counselling for type 2 diabetes (T2D) and cardiovascular disease risk reduction. The lifestyle modification program will support daily ambulatory activity and low glycemic index food intake among women with previous GDM.

Methods:

To achieve the study objective, the HEALD-GDM lifestyle modification program already proven effective for adults with T2D among women with previous GDM within 12 months postpartum will be evaluated. Women will take part in either the HEALD-GDM program (intervention) or in usual care (control). To evaluate the effectiveness of HEALD-GDM, a randomized, two-arm, before and after study design is proposed. Potentially eligible participants will be recruited from Diabetes in Pregnancy Clinics in Calgary and Edmonton, Alberta. Following identification of eligible participants, the investigators will randomize 100 participants to either the HEALD-GDM program or to usual care control (i.e., 50 per group). A Canadian Society of Exercise Physiology certified instructor (Exercise Specialist) trained in HEALD-GDM delivery will lead the program. Group-based classes will be held at community recreational centres in Calgary and Edmonton (one site each) in months one and four of the 24-week HEALD-GDM program. Theory-guided peer-led telephone counselling will supplement the program. HEALD-GDM focuses broadly on T2D prevention through lifestyle modification and will be based on a proven effective pedometer-based active living behaviour.

The primary outcome will be change in objectively measured moderate and vigorous physical activity at assessment appointments (baseline and 24 weeks). Secondary outcomes include: 1) body mass, 2) glycemic control (hemoglobin A1c), 3) musculoskeletal and cardiorespiratory fitness, 4) dietary intake, 5) metabolic biomarkers, 6) health-related quality of life (HRQL), social-cognitive mediators and 7) mental health.

Significance:

Evidence for appropriate lifestyle modification programs for this high-risk population is lacking. This study will serve to inform best practices for diabetes and cardiovascular disease risk reduction through known modifiable risk reduction targets such as healthy eating and active living.

Inclusion Criteria:

• laboratory confirmed previous and recent (within last 12 months) gestational diabetes mellitus • informed consent

Exclusion Criteria:

• unable to provide informed consent or unwilling to participate in the study
• unable to read, understand and converse in English
• contraindications based on the Canadian Society for Exercise Physiology Physical Activity Readiness Questionnaire Plus (PAR-Q+)
• currently enrolled in other diabetes-related research studies
• pregnant or planning another pregnancy in the next 12 months (any participants becoming pregnant at any point during the study will only contribute data prior to their pregnancy date)
• hemoglobin A1c >6.5% or clinical suspicion of type 1 or type 2 diabetes