Impact of lifestyle intervention on vitamin D, Adiponectin, Insulin-like growth factor 1 and Proneurotensin in overweight individuals from the Middle East.

BACKGROUND

Immigrants from the Middle East (ME) have a higher prevalence of type 2 diabetes (T2D) compared to the native-born Swedish population. In individuals free from T2D, ME immigrants are more insulin resistant and have lower levels of adjusted insulin secretion (Disposition index, DIo) compared to Swedish-born individuals. The ethnic differences are not fully explained by traditional risk factors. This has raised the question as to whether hormonal factors other than insulin are involved, contributing to higher T2D risk in ME immigrants.

AIMS: In ME immigrants at high risk of developing T2D, we aimed to study the effect of a randomized culturally adapted lifestyle intervention on the levels of Vitamin D (25(OH)D), insulin-like growth factor 1 (IGF-1), Pro-neurotensin (Pro-NT) and Adiponectin. Furthermore, we aimed to study if the effect of the intervention was associated to these hormones, or if a direct effect of the intervention remained after accounting for these.

METHODS

In this culturally adapted randomized controlled trial of four months duration, eligible ME immigrants at high risk of developing T2D identified in the MEDIM cohort were invited to participate. The intervention group (N= 35) received a culturally adapted lifestyle intervention program consisting of seven group sessions and cooking classes. The control group (N= 32) were given treatment as usual with oral and written information to improve their lifestyle habits. Using mixed models' linear regression analysis, the changes in the levels of 25(OH)D, IGF-1, Adiponectin and Pro-NT were assessed by comparing the groups and we further studied the effects of the changes on insulin action and secretion.

RESULTS

The adjusted levels of 25(OH)D significantly increased in the intervention group compared to the control group (β for the effect of the intervention on 25(OH)D: 0.061, 95 % CI 0.009-0.113, P = 0.023). The increase in insulin sensitivity index (ISI) observed in the intervention compared to the control group was altered after adjusting for 25(OH)D: 0.129, 95 % CI -0.016-0.274, P = 0.078). IGF-1, Adiponectin and Pro-NT did not significantly influence the change over time concerning insulin secretion.

CONCLUSION

Lifestyle intervention increases the adjusted levels of 25(OH)D. Moreover, the effect of the lifestyle intervention on insulin action and secretion was altered when adjusting for 25(OH)D.