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Study suggests neighborhood design may help prevent the risk of poor blood sugar control among immigrant populations

Diabetologia

Neighbourhood designs that promote walking may reduce the risk of prediabetes in immigrant populations, according to new research being presented at this year's European Association for the Study of Diabetes (EASD) Annual Meeting in Lisbon, Portugal (11-15 September).

Prediabetes is when blood sugar control is impaired but not yet to the extent of full blown diabetes. On average, 5 to 10% of people who have prediabetes convert to type 2 diabetes each year.

Previous research on urban environments have shown that immigrants living in less walkable neighbourhoods are at a higher risk of developing diabetes compared to those living in more walkable neighbourhoods. In this study, Dr Gillian Booth, Ghazal Fazli and colleagues at St. Michael's Hospitals and the Institute for Clinical Evaluative Sciences, Toronto, ON, Canada examined whether walkable environments have a favourable impact at earlier stages in the natural history of type 2 diabetes development -- the transition from normal blood sugar levels to prediabetes - across different ethnic groups.

Walkability can be defined as the extent to which neighbourhoods support pedestrian activity, and is affected by such factors as the number of stores and services within walking distance, the number of connections between streets, and population or residential density. The study compared the incidence of prediabetes among immigrants to Canada living in the highest walkability (the highest 20%) versus lower walkability areas (the other 80%) within cities in Southern Ontario (Toronto and surrounding communities, Hamilton, London and Ottawa).

The authors also examined whether walkability altered the differences in prediabetes development seen in higher versus lower risk ethnic groups. The subjects were 193,899 adults between the ages of 20 and 85 (mean age 40 years), including individuals who immigrated from Sub-Saharan Africa and the Caribbean (20,324); South Asia (38,441); South-East Asia (18,541) and Western Europe (14,227).

After adjusting for age, sex and area income, it was found that all non-Western European populations had a higher incidence of prediabetes. However, the authors noted that "these effects were more marked in low walkability neighbourhoods and reduced or eliminated in high walkability areas".

In the Sub-Saharan African and Caribbean population, for example, the incidence of prediabetes was twice as high as Western European populations among those living in low walkability areas but only 20% higher among those living in high walkability areas. Likewise, West Asian/Arab populations living in low walkability areas had a 50% higher incidence when compared to their Western European counterparts, but no significant association was found in high walkability districts. The interaction between ethnicity and walkability was less pronounced among South Asians, who were found to have approximately twice the prediabetes incidence of Western Europeans irrespective of walkability of their neighbourhood. For adults over 65, the effects of ethnicity on prediabetes risk were less pronounced in both low and high walkability areas, but the effects of walkability persisted.

The authors conclude: "The risk of prediabetes development among immigrant populations may be amplified by unexpected factors such as neighbourhood designs. We believe further research is needed to guide the design of population interventions and policies to target the social and environmental factors perpetuating the development of prediabetes (and subsequent diabetes) among high-risk populations."

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