The Effectiveness of Indigenous Knowledge-Based Lifestyle Interventions in Preventing Obesity and Type 2 Diabetes Mellitus in Indigenous Children in Canada: A Systematic Review

Introduction

In the general population, obesity and type 2 diabetes mellitus (T2DM) are significant contributors to the global noncommunicable disease burden.^1,2 Both diseases have made generational leaps and now impact children. In Canada, one-in-three children have an elevated body mass, and these high overweight and obesity rates are driving T2DM in Canada and globally.³

Indigenous communities in Canada are disproportionately impacted by obesity and T2DM.^1,2 The incidence of T2DM in Indigenous children is up to 12.45/100,000 persons/year–one of the highest in the world, and Indigenous children account for almost half of the newly diagnosed T2DM cases annually.⁴

The high rates of adverse metabolic outcomes in Indigenous communities in Canada are part of the legacy of colonization-driven intergenerational trauma, social disadvantage, racism, poverty, food insecurity, and change in dietary choices and traditional physical activities.^5–12

Pediatric T2DM is an aggressive disorder with associated conditions such as nephropathy, dyslipidemia, obstructive sleep apnea, polycystic ovaries syndrome, and fatty liver disease.^13–15 There is an urgent need for prevention and treatment strategies to manage obesity and T2DM to improve health outcomes in this population.^16,17

Tackling obesity and diabetes will require interventions to be owned, developed, and controlled by the Indigenous communities to ensure relevance, sustainability, and a nuanced approach that honors the unique culture and the Indigenous Ways of Knowing.^11,18

Indigenous knowledge-based view of health encompasses the holistic vision of physical, mental, emotional, and spiritual dimensions, and it is connected to the land and the culture of Indigenous peoples.¹⁹ This vision of health needs to be at the core of culturally appropriate Indigenous-led interventions to maximize their success.²⁰

The objective of this systematic review was to assess the impact of Indigenous Knowledge-based lifestyle interventions on the prevention of obesity and T2DM in Indigenous children in Canada.

Methods

This systematic review was registered with the International Prospective Register of Systematic Reviews (PROSPERO CRD42017072781) and is reported in compliance with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement (Table S1).²¹ The protocol describing the methods for this review has been published.²²

Main Outcomes

For obesity, the changes in Body Mass Index (BMI) z-score with the implementation of the intervention was utilized as the main outcome. We attempted to define prevention as either the inclusion of populations that live with overweight and demonstrating a stabilization or reduction of BMI z-score, or those with obesity who had a drop in the BMI z-score to the overweight or non-obesity levels. It also encompassed populations with no obesity with stabilization of the BMI z-score with the intervention.

The diagnosis of T2DM was based on standardized criteria for the second main outcome of this review.²³

Other Outcomes

The other outcomes pursued included changes in total adiposity as measured by Dual Energy X-Ray Absorptiometry (DXA) scans or bioelectrical impedance. Central adiposity was measured using waist circumference (WC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), and subcutaneous fat was measured using skinfold thickness if reported. Other aims included assessing changes in lifestyle factors, including nutrition and fitness and metabolic profiles including glucose and lipid homeostasis.

Eligibility Criteria

We planned to include primary research reports of randomized controlled trials (RCTs), quasi-experimental studies, and uncontrolled before-and-after study designs, when available. The targeted studies recruited Indigenous boys and girls of First Nations, Inuit, or Métis communities who were <18 years old. Studies were included regardless of the publication date, setting, or language. Studies were excluded if participants were diagnosed with T2DM as they have already developed one of the main study outcomes.

Search Strategy

We searched several databases from inception to February 22nd, 2022. We included the Medical Literature Analysis and Retrieval System Online (MEDLINE), the Cochrane Database of Systematic Reviews, the Cochrane Controlled Register of Trials, The Cumulative Index to Nursing and Allied Health Literature (CINAHL), Excerpta Medica Database (Embase), SportDiscus, Web of Science, American Psychological Association (APA) PsycINFO and iPortal (an Indigenous studies portal research tool).²⁴ The search strategies were created in collaboration with a Senior Health Sciences Librarian (Appendix 1).

The grey literature search was conducted in the ProQuest Dissertations and Theses A&I and ClinicalTrials.gov. Reference lists of included articles were also searched during full-text screening to identify potentially eligible studies.

Study Selection and Data Abstraction

Two teams of two independent reviewers screened the titles, abstracts, and full-text articles against the eligibility criteria. The reviewers met at every stage to review disagreements, and a third reviewer was available to arbitrate persistent differences.

Risk of Bias and Quality Assessments

We planned to assess the risk of bias of RCTs by using the revised tool from the Cochrane Collaboration 2 (RoB 2.0).²⁵ Non-randomized studies were to be evaluated using the Non-Randomized Studies - of Interventions tool (ROBINS-I), and uncontrolled studies were to be assessed using the University of Alberta Evidence-based Practice Center (UAEPC) assessment tool.^26,27 To determine confidence in the overall evidence base, we used the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach.²⁸

Statistical Analysis

We used the chi-square test of homogeneity and inconsistency index (I²) to evaluate heterogeneity. The Cochrane Collaboration targets were used, with a p-value of <0.1 and I² of 75% indicative of heterogeneity cutoffs, respectively.²²

We did not use funnel plot or Egger’s test to evaluate small study effect as initially planned due to the lack of studies. Instead, we made estimates based on unpublished data from conference abstracts or registered trials.²⁹ A random effects meta-analysis was planned but not performed for BMI z-score and WC due to the absence of studies reporting on similar populations, study designs, methods, outcomes and study heterogeneity.

Results

Search results

Database searches retrieved 3760 records, and grey literature searches retrieved 31 records (Figure 1). Eleven additional documents were identified from reference lists. After screening articles and removing duplicates we identified ten eligible studies in this systematic review, including four cross-sectional studies with a control arm and six before-and-after cross-sectional studies.^30–39

Figure 1 Article screening process flow chart.

Study Characteristics and Results

Table 1 reports the characteristics of the included studies. Nine studies involved First Nations communities^{30–32,34,36–39} and one study was reported from a Métis community.³³

Table 1 Characteristics of Included Studies

All studies focused on school or community obesity-based lifestyle interventions (intervention group n=1328, controls n=382). All studies employed a participatory action-based approach to actively engage the community. Participatory action research (PAR) is specifically undertaken by researchers and communities they work with to ensure that interventions are curated to the specific needs of the community.³³

Seven studies implemented a combination of diet, physical activity, and psychological support components and focused on self-esteem, attitude, and healthy relationships.^{30–33,35,38,39} Two studies implemented diet and physical activity-based interventions,^34,37 and one focused on physical activity alone.³⁶ The duration of the interventions ranged from 4 to 48 months in six studies. The remaining four studies reported annual data from ongoing programs.

Notable Programs and Results

Several unique models were reported in the studies. Notable school and community-based programs included the Sandy Lake Health and Diabetes Project (SLHDP) in Ontario, the Kahnawake School Diabetes Prevention Project (KSDPP) in Quebec, EarthBox Kids in Alberta and Healthy Buddies in British Columbia.^{30,32,34,35,37,38}

The SLHDP is a non-randomized school-based diabetes prevention intervention that was established in 1991. The intervention incorporates Indigenous learning methods and aims to reduce the high prevalence of diabetes in the community via promoting physical activity and healthy nutrition.³⁴ The data were reported over two periods including 1998–1999 and 2005–2007.^34,37 Overall, both studies evaluating the SLHDP found an increase in mean BMI (kg/m²) (Saksvig et al (2005) – pre: 20.5±4.3; post: 21.5±4.8; p<0.001; Kakekagumick et al (2013) – pre: 20.4; post: 23.1; p<0.001) and body fat percentage (Saksvig et al (2005) – pre: 29.8 ± 10.7%; post: 31.0 ± 10.8%, p-value< 0.001; Kakekagumick et al (2013) – pre: 32.0; post: 35.8%, p-value<0.001) with the intervention.^34,37 However, the program did report that students had improved knowledge about healthy foods and increased dietary self-efficacy.³⁴

The KSDPP is a non-randomized long-term school- and community-based project in the Kahnawake community. This program prioritizes community involvement and ownership through promoting healthy habits among school-age children.^32,40 Two studies reported the results, with data reported over eight years for the intervention group, and two years for the control group in one study.^32,35 Only data over the two-year period for the intervention group where comparison data were available.³² Overall, the first study evaluating the KSDPP reported an increase in BMI and no improvements in physical activity or dietary consumption.³² Additionally, there was a less rapid increase in subscapular skinfold thickness (mm) in the intervention (pre: 7.62 ± 0.35 mm; post: 10.36 ± 0.49 mm) compared to the control group (9.05 ± 0.67 mm; 14.88 ± 0.94 mm) of children from a school in the Kanien’keha´:ka community located around 200 miles from the study community.³² The second study reported no reduction in BMI over four years of intervention.³⁵ However, self-reported physical activity levels, defined as percentage of students who completed ≥30 mins of physical activity per day, increased over the intervention period (pre: 71%; post: 94%; p<0.001).³⁵

The EarthBox Kids is a community-based participatory action research intervention in partnership with the University of Alberta, school staff, a community elder and an agriculture education specialist. This program was based on the social and cultural norms of the Alexander community in Alberta, and involved a 7-month classroom gardening activity and a 4-month weekly snack program.³⁸ At the end of the intervention, children reported fruit preferences that were similar to baseline, and had an improved vegetable preference score only for tomatoes. There were no data reported on body mass measures (Table 2 and Table 3).

Table 2 Effects of interventions on primary outcome; BMI z-score

Table 3 Effects of interventions on other outcomes

The Healthy Buddies (HB) school-based, peer-led program comprises three key components including healthy eating, physical activity and self-esteem supports. One study reported an analysis of three Indigenous schools located in a remote Tsimshian First Nation community in British Columbia.³⁰ This program was also one of the only interventions that specifically contained the self-esteem component. The latter scores were reported to increase in the intervention group (pre: 74.6±12.9; post: 77.3±12.2) and decrease in the control group (pre: 76.7±14.9; post: 71.7±14) (interaction (time and group) p=0.005).³⁰

Anthropometric Measures Changes with the Interventions

Two repeated cross-sectional studies including BMI z-score and WC were conducted in British Columbia and Manitoba and employed peer-led, school-based interventions.^30,31 The interventions were effective in improving the BMI z-score (Ronsley et al (2013) – pre: 1.10±0.99; post: 1.04±0.94; p=0.028; Eskicioglu et al (2014) – pre: 1.27 (1.17–1.37); post: 1.22 (1.11–1.32; p=0.007 between groups) and WC (Ronsley et al (2013) – pre: 77.1 ± 18.8 cm; post: 75.0 ± 17.1; Wilcoxon p<0.0001; Eskicioglu et al (2014) – pre: 77.8 (75.6 to 80.1); post: 78.2 (75.9 to 80.5); p<0.001 between groups) in the intervention group.^30,31 One uncontrolled study (n=133) found no change in BMI z-score (pre: 1.12±0.86; post: 1.10±0.87; p-value 0.288) and increased WC z-score with the intervention (pre: 0.46±1.07; post: 0.57±1.04, p<0.05).³⁶ Another uncontrolled study (n=35) reported an increase in BMI z-score (pre: 1.0; post: 1.3, p-value 0.001) and WC (pre: 74.8 cm; post: 84.1 cm, p-value <0.001) with the intervention (SLHDP) from baseline.³⁷

Lifestyle Measures

Of the nine studies that reported on dietary changes with the intervention, two uncontrolled studies^34,39 reported a non-significant trend of dietary improvements.^{30,32,33,35–38} One study reported improvements in daily intake of fruits and vegetables, however most participants did not meet the recommended intake for most food groups.³⁹ No studies reported changes in metabolic outcomes with interventions including glucose, insulin, Glycated Hemoglobin A1c (HbA1c), and lipid profile.

Risk of Bias and Overall Quality of Evidence

The UAEPC checklist was used to assess the risk of bias for six uncontrolled before-and-after studies (Table S2).^34–39 All studies had consecutive recruitment. Two studies were rated as having a low risk of bias due to standardized measurement methods and appropriately addressing missing data.^35,36 The remaining four studies were rated at an overall unclear risk of bias due to the absence of independent outcome assessors.^34,37–39 Furthermore, the outcome assessors across all studies were not blinded, which may potentially contribute to reporting bias for dietary recall and physical activity.

For the four non-randomized controlled trials,^30–33 the ROBINS-I tool was used (Table S3). All four studies had a low risk of bias in the selection of participants and data reporting. The bias due to confounding and deviations was rated as moderate due to the potential for deviation from the intended interventions. Two studies^32,33 had a low risk of bias in the classification of intervention, but the other two^30,31 were rated as moderate due to logistical challenges. One study, for example, was originally designed to be a pre-/post-evaluation of the intervention, however, one of the three schools participating did not end up implementing the intervention. Therefore, the research team treated the non-participating school as a naturalistic control group in the analysis.³⁰ Further, none of the studies were blinded, leading to the overall estimation of a serious risk of bias for self-reported outcomes and a moderate risk of bias for objective outcomes.

For GRADE, the overall quality of evidence for BMI z-score and WC was very low (Table S4). The risk of bias was serious in the quality of the evidence. The concerns about inconsistency and indirectness were not serious. As we were unable to perform the meta-analysis, this was a limitation in evaluating heterogeneity. Imprecision was serious due to the small sample size.⁴¹ The quality of evidence across studies was also downgraded due to the lack of randomization. We did not find conference abstracts or registered trials without publications, so it was unclear if small study effect was significant.

Discussion

Over the past few decades, Canada has not been immune to the global rise in pediatric obesity and T2DM. These disorders are especially prevalent in Indigenous children in Canada, so there is an urgent need to define culturally appropriate, Indigenous Knowledge-based interventions to manage obesity and T2DM.

School- or community-based interventions that integrate traditional knowledge can be especially relevant to remote communities and provide a locally sustainable care model to treat obesity and prevent T2DM. The studies evaluating obesity and T2DM prevention programs for Indigenous children in Canada were non-randomized and provided conflicting results. With these limitations in mind, non-randomized studies reported modest reductions in BMI z-score and WC compared to controls, with a very low quality of evidence.^30,31 These studies employed a peer-led component in schools, which provides a feasible, sustainable, and cost-effective solution.^30,31,42 Two uncontrolled studies reported the BMI z-score and WC outcomes with contrasting results.^36,37

A recent scoping review aimed to identify existing school-based nutrition programs for Indigenous children in Canada and evaluate their success identified 34 unique programs addressing various health components.¹⁸ Most of the interventions implemented educational components (56%), partnerships, such as engaging elders (59%), with 62% of the interventions being owned and led by Indigenous communities.¹⁸

Community- and school-based participatory research should focus on local ownership and strong community leadership and participation. The communities have the option of selecting partners that can be engaged as needed to support study design, implementation, and evaluation guided by the communities’ specific goals, preferences, and values. Indigenous Knowledge and practices need to be central to research design, conduct, and evaluation and the data must be under the control of and are possessed by the community.^18,19 Understanding the needs and design of interventions directed at Indigenous children in urban settings is an area where more data are needed.

One of the strengths of this review involves the comprehensive search strategy and the inclusion of all relevant literature by expanding our searches to grey literature and reference lists. We also used iPortal, a database primarily focused on Indigenous peoples of Canada, to identify relevant studies specific to Indigenous health.²⁴ We also used standardized tools, including the GRADE approach to evaluate the confidence in recommendations based on the evidence.

One limitation of the review was related to the location of the study conduct. While studies primarily focused on Indigenous participants living on reserves in Northwestern Ontario, Manitoba, British Columbia, and Quebec, no studies included Indigenous children living in urban settings. As more than half of Indigenous people in Canada live in urban areas, it is crucial to define ways to create culturally appropriate interventions for these populations informed by needs, preferences, and values.^43,44

Although four studies included a control group,^30–33 none of the studies were randomized controlled trials (RCTs), and sample sizes were small, which limits confidence in the evidence.⁴¹ Lastly, one of the goals was to evaluate the effect of these interventions on the prevention of T2DM, and no studies reported data on T2DM prevention or changes in metabolic health parameters. Preventing and treating obesity is the most promising approach to preventing T2DM, as obesity is one of the main drivers of this complex disease.

Conclusion

In conclusion, this systematic review highlights the need for traditional knowledge-based lifestyle interventions to manage obesity in Indigenous children in Canada that may lead to improvements in body mass and adiposity measures and potentially prevent diabetes. Further research that is Indigenous-led, owned, with adequately powered RCTs that incorporate Indigenous Knowledge and ways of knowing into obesity treatment and strategies to prevent T2DM is urgently needed.

Additionally, future studies need to standardize the reporting of metabolic outcome measures and assess the impact of Indigenous Knowledge-based lifestyle interventions on preventing T2DM in urbanized Indigenous communities. As childhood obesity often tracks into adulthood,^45–49 longitudinal studies are urgently needed to measure the impact of attempts to alter the obesity trajectory in childhood that may prevent the cardiovascular and metabolic health concerns observed in Indigenous communities during adulthood.