Ethnic differences in the contribution of insulin action and secretion to type 2 diabetes in immigrants from the Middle East compared to native Swedes.
OBJECTIVE
We investigated insulin action (insulin sensitivity index, ISI) and insulin secretion (oral disposition indices, DIo) and studied metabolic, demographic and lifestyle-related risk factors for type 2 diabetes and insulin action, in the largest non-European immigrant group to Sweden, immigrants from Iraq and native Swedes.


METHODS
Population-based, cross-sectional study conducted 2010-2012 including residents 30-75 years of age born in Iraq or Sweden, in whom oral glucose tolerance tests were performed and sociodemography and lifestyle behaviors were characterized.


RESULTS
In Iraqis compared to Swedes, ISI was more impaired (76.9 vs. 102.3, p<.001) whereas corrected insulin response CIR was higher (226.6 vs. 188.6, p=.016). However, insulin secretion was inadequate given the substantial insulin resistance, as indicated by lower DIo indices in Iraqis than in Swedes (DIo 12,712.9 vs. 14,659.2, p<.001). The crude ethnic difference in ISI was not offset by traditional risk factors like waist circumference, body mass index or family history of diabetes. In Iraqis, ISI conveyed somewhat higher odds of type 2 diabetes than in Swedes (odds ratio OR 0.98, 95% CI 0.97-0.99) vs. OR 0.95, 0.92-0.99), as indicated by an interaction between country of birth and ISI (Pinteraction=.044).


CONCLUSIONS
This study reports ethnic differences in the contribution of insulin action to type 2 diabetes. Our data suggests that the impaired insulin action observed in immigrants from the Middle East to Sweden is not fully explained by established risk factors.
Department of Clinical Sciences, Lund University, Skåne University Hospital, Sweden; Genetic & Molecular Epidemiology, Lund University, Malmö, Sweden. Electronic address: Louise.Bennet@med.lu.se.
Louise
L
Bennet
Department of Clinical Sciences, Lund University, Skåne University Hospital, Sweden; Department of Diabetes and Endocrinology/Lund University Diabetes Centre, Skåne University Hospital, Malmö, Sweden.
Leif
L
Groop
Department of Clinical Sciences, Lund University, Skåne University Hospital, Sweden; Genetic & Molecular Epidemiology, Lund University, Malmö, Sweden; Department of Nutrition, Harvard School of Public Health, Boston, MA, USA; Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
Paul W
PW
Franks
D000328:Adult; D000368:Aged; D018912:Arabs / Q000208:ethnology*; D001823:Body Composition; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000208:ethnology*; D054242:Emigrants and Immigrants / Q000706:statistics & numerical data*; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D000078790:Insulin Secretion; D007493:Iraq / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D055105:Waist Circumference; D044465:White People / Q000208:ethnology*
D007328:Insulin
Insulin action; Insulin secretion; Middle East; Type 2 diabetes; Waist circumference