key: cord-297047-ew9l9yjd
authors: Ali, Shahmir H.; Misra, Supriya; Parekh, Niyati; Murphy, Bridget; DiClemente, Ralph J.
title: Preventing Type 2 Diabetes among South Asian Americans through community-based lifestyle interventions: a systematic review
date: 2020-08-21
journal: Prev Med Rep
DOI: 10.1016/j.pmedr.2020.101182
sha: 
doc_id: 297047
cord_uid: ew9l9yjd

Ethnic South Asians Americans (SAAs) have the highest relative risk of type 2 diabetes mellitus (T2DM) in the United States (US). Culturally tailored lifestyle interventions have the potential to promote South Asian diabetes prevention; however, the extent of their use and evaluation in US settings remains limited. This systematic review characterizes and evaluates outcomes of community-based lifestyle interventions targeted towards T2DM indicators among South Asians living in the US. A PRISMA-informed search of Pubmed, Embase, Cochrane, Web of Science, and clinical trial registry databases using key words pertaining to South Asians migrants and diabetes indicators (glucose and insulin outcomes) was conducted of community-based lifestyle interventions published up until October, 31 2019. Of the eight studies included in the final synthesis, four interventions focused on cultural and linguistic adaptations of past chronic disease prevention curricula using group-based modalities to deliver the intervention. Hemoglobin A1c (A1c) was the most common outcome indicator measured across the interventions. Three of the five studies observed improvements in indicators post-intervention. Based on these findings, this review recommends 1) greater exploration of community-based lifestyle interventions with high quality diabetes indicators (such as fasting blood glucose) in ethnic South Asian American communities, 2) expanding beyond traditional modalities of group-based lifestyle interventions and exploring the use of technology and interventions integrated with passive, active, and individualized components, and 3) development of research on diabetes prevention among second generation South Asians Americans.

In 2017 approximately 30.3 million people in the US were living with diabetes, creating 27 an epidemic cost of 327 billion [1, 2] . Ethnic SAAs have a disproportionately high burden of 28 T2DM; ethnic Asian Indians for instance have a 2.8 times greater relative risk of T2DM as 29 compared to whites and 1.3 greater risk compared to the Asian aggregate [3] . In clinical and 30 research settings, the primary outcome indicators used to measure and screen for T2DM include 31 measures of blood glucose, such as A1c, fasting plasma glucose (FPG), the oral glucose tolerance 32 test (OGTT), and measures of insulin resistance, such as the Homeostasis Model Assessment 33 (HOMA) and the Quantitative Insulin Sensitivity Check Index (QUICKI) [4, 5] . Lifestyle factors 34 (such as poor diet and exercise) have been recognized as key contributors to the sharp rise in T2DM 35 States attracts a significantly greater population of highly educated, first-generation South Asian 42 migrants [11] [12] [13] . The significant differences in socio-demographics, relevant to intervention 43 design between South Asian migrants living in the US versus those in the UK and Europe, suggests 44 the need for region-based intervention analysis. Likewise, given the rise of pre-diabetes in the 45 United States, preventing diabetes incidence is also of paramount importance [2] . 46 47

Although diabetes management remains a concern among many ethnic South Asians in the 49 United States, there has been a growing impetus to focus attention on diabetes prevention among 50 individuals with pre-diabetes and patients who have not yet developed diabetes but may be at-risk 51 [14] . Diabetes prevention programs focus on promoting health-protective lifestyle changes; 52 however, these programs must be tailored in a culturally sensitive way to optimize programmatic 53 effectiveness [14] . 54 55

In the United States, the large, multi-ethnic, multi-center Diabetes Prevention Program 56 (DPP) has provided robust evidence for diabetes prevention [15] . However, the program lacks a 57 separate analysis of ethnic South Asian community outcomes. Its generalizability for the Asian 58

American migrant community has also been criticized, in part, due to limited cultural relevance in 59 the diet, exercise, and behavior change components of the program [16] . Indeed, with the observed 60 need for cultural precision in diabetes prevention campaigns, there is a gap in understanding the 61 impact that existing diabetes prevention interventions (with varying levels of cultural sensitivity 62 in design) have had on at-risk subpopulations such as ethnic SAAs. 63 64 Community-based lifestyle interventions are particularly promising for diabetes prevention 65 among ethnic SAAs. The strength of this approach lies in a number of key aspects [17] . First, 66 targeting an intervention at the population level among individuals with varying levels of risk 67 allows for maximum reach and access to intervention materials, especially relevant for 68 communities such as ethnic SAAs who may not be able to afford or seek clinical services [18] . Clinicaltrial.gov, and Google Scholar. Authors of protocols, registered trials, and studies with 91 only baseline data were individually contacted to assess if post-intervention data was available for 92 inclusion (three contact attempts were made of each author). 93

The detailed search strategy employed in the formal database search is displayed in Table  95 1. Key words used included community-based lifestyle intervention related terms informed from 96 past systematic reviews along with terms focused on South Asian immigrant populations (those 97 ethnically identifying as Indian, Pakistani, Bangladeshi, Sri Lankan, Nepalese, Bhutanese, or 98

Maldivian), and terms relating to diabetes, including glucose or insulin indicators (A1C, plasma 99 blood glucose, 2h post load glucose, insulin sensitivity, among others) [20] . 100

A screening reliability test was conducted by two independent reviewers (SA and BM) of 103 60 abstracts within the full screening sample, followed by complete abstract and title screening. 104

Studies conducted on ethnic SAA populations above the age of 18 were within the scope of the 105 study. A study was included if it satisfied the following criteria. First, the study had to focus, at 106 least partly, on a specific South Asian population (including the seven identified South Asian 107 nationalities) that were residing in the US at the time of study. Second, the study must discuss a 108 community-based intervention defined as an "approach directed to a population rather than 109 individuals, implemented in community settings rather than hospital or health care settings, and 110 approaches coordinated through friends, family, neighbors, community members, worksites, 111 schools or primary health care centers" [20] . Third, the study had to include at least baseline data. 112

Fourth, the study had to include biomarkers commonly used to assess diabetes risk: blood glucose 113 or insulin related indicators. A study was excluded if it was a review, lacked an ethnic SAA sample, 114 focused exclusively on diabetes management among individuals with T2DM, or lacked a 115 community-based component (e.g., exclusively structural or clinic/hospital-based). 116 117

A data extraction form was developed by the study authors and pilot tested before being 119 implemented for the final study sample. Data extracted included study participant characteristics, 120 intervention characteristics, and outcome variable data. Full-text assessment and data extraction 121 were conducted by two independent reviewers (SA and SM), and the senior author (RD) served as 122 a tiebreaker when a consensus could not be reached. If demographic information for control and 123 intervention group was presented separately, a weighted average was calculated for the variables 124 of interest. 125

The National Heart, Lung, and Blood Institute (NHLBI) study quality assessment tool was 127 applied to all included studies by two independent reviewers (SA and SM). One of two NHLBI 128 checklists were used, depending on study design: controlled intervention studies or before-after 129 (pre-post) studies with no control group [21] . Given the heterogeneity in the study designs, the 130 checklists were supplemented by a brief narrative quality assessment focused on aspects of 131 feasibility, acceptability, retention, and the meaningful role of cultural and community-based 132 design and adaptation measures. Eight studies were included in the final qualitative synthesis, including two randomized 144 controlled trials [24, 25] , two two-group pre-post studies [26, 27] , three one-group pre-post studies 145 [23, 28, 29] , and one experimental study with only baseline data [30] ( The quality of the studies was generally good for their study design, with all but two studies 175 scoring in the ("Good") category on the three-option ("Good, Fair, Poor") NHLBI assessment tool. 176

Most studies were pilot studies and did not include a control group. Among controlled studies, a 177 few used randomizations but others, such as Islam et al., did not due to negative community perceptions toward randomization [26] . Most studies compared the characteristics of those who 179 dropped out of the study with those who stayed in the study (with issues of time-commitment being 180 a salient reason for attrition across the interventions); however, only one study included a full 181 qualitative process evaluation through participant interviews to understand barriers and facilitators 

The structure of the community-based lifestyle interventions varied considerably (Table 4) . Diabetes prevention among ethnic South Asians Americans is a major public health 278

concern. This review sought to systematically assess characteristics and effectiveness of 279 community-based lifestyle interventions involving T2DM blood glucose and insulin indicators. greater socio-economic advantage, more favorable attitudes towards physical activity, exercise 332 more, and have less pressure to conform to traditional norms of diet and exercise [38] [39] [40] . Indeed, the fact that almost all studies in the current sample did not specifically exclude second-generation 334 or US-born ethnic SAAs suggests a need for greater sampling of second-generation South Asians 335 (or potentially interventions specifically targeting the community) to provide a better 336 understanding of the general applicability of community-based lifestyle interventions and provide 337 implications for future work. Specifically, mixed-methods formative research among second-338 generation ethnic SAAs my identify certain foods or exercise behaviors more salient or culturally 339 acceptable in this sub-population compared to first-generation migrants, which can then directly 340 be integrated into diabetes prevention interventions targeting the community. suggest that significant trends may not be reflected across all diabetes prevention outcomes [24] . 362

Indeed, there is evidence highlighting the extent to which different blood glucose or insulin 363 resistance outcomes may have uniquely salient roles in explaining diabetes prevalence across 364 racial groups, including among ethnic South Asians [42, 43] 

SAA diabetes prevalence observed that low β-cell function and insulin resistance was particularly 366 high among South Asians and called for further research to identify the biological pathways and 367 mechanisms behind diabetes progression among ethnic South Asians [43] . Similarly, the 368 measurement of A1c in distinguishing between individuals with pre-diabetes and those without 369 diabetes (the main focus of diabetes prevention interventions) has been shown to be lower than its Preventing T2DM among ethnic SAA communities remains a pressing public health 397 concern in the US, and community-based lifestyle interventions present a promising opportunity 398 to address this challenge. This review provides information on the potential efficacy and gaps 399 pertaining to community-based lifestyle intervention design to inform further research and health 400 promotion activities in this field. Based on the findings of this study, we have the following 

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