Methods Using the Qatar 2012 WHO STEPwise approach to surveillance survey, a subsample of 1224 Qatari participants aged 18–64 years was selected.
Subjects had their fasting blood glucose levels tested, had not been diagnosed with or treated for diabetes, had a fasting time 12 hours and were not pregnant.
In addition, early detection is critical to helping define an individual's subsequent risk for developing type 2 diabetes.12 20The disease pathway of type 2 diabetes is defined by stepwise increases in blood glucose level and consists of three stages.
The first stage, known as normoglycemia, encompasses the normal glucose range of 65–99 mg/d L.
SEM and factor analysis of diet, physical activity and sociodemographic characteristics were used to describe the sociodemographic, latent behavioral, anthropometric and metabolic variables affecting normoglycemia, pre-diabetes and diabetes based on the model used by Bardenheier 42 SEMs are often best understood using a graphic where direct effects are depicted as vectors stemming from an independent variable (exposure) and pointing towards a dependent variable (outcome).
A confounder, according to the use of these directed acyclic graphs, is depicted as a variable with direct effects on both the exposure and the dependent variable.28 Correlations between the measurement errors of two variables are represented by two-headed curving arrows, in which case only the measurement error terms were defined as correlated.41 42Analyses proceeded in two stages.
We also included measures of dietary quality based on the STEPS tool.35 These included fruit and vegetable intake using the 7-day average recall dietary assessment of the STEPS questionnaire.29 39 With these two dietary components we created Healthy Eating Index—2010 (HEI) scores.40 The HEI is a measure of diet quality that is independent of quantity and that can be used to assess compliance with the US Dietary Guidelines for Americans and monitor changes in dietary patterns.40 It is based on a score between 0 and 5, where 5 is the highest quality diet.
We also included as a measure of dietary quality the number of days per week the participants ate out of their homes and the self-reported weekly frequency of fast food consumption.
We also found that physical activity levels negatively affect BMI (−0.148) and positively affect high-density lipoprotein (HDL) (0.106); sociodemographic background negatively affects diet (−0.522) and BMI (−0.352); HDL positively affects total cholesterol (0.230) and has a negative effect on BMI (−0.108), triglycerides (−0.128) and waist circumference (−0.104).
Diet has a positive effect on triglycerides (0.281) while family history of diabetes negatively affects total cholesterol (−0.104).
Analysis with SEM permits us to define local interactions of sociodemographic, behavioral, anthropometric and metabolic variables in terms of direct effects and indirect (ie, mediator) effects on diabetes status.28 Unlike traditional regression models, SEM can simultaneously assess all relevant regression pathways as either independent and/or dependent factors that play a role in type 2 diabetes.28WHO developed the STEPS to support countries in building and strengthening their capacity to conduct NCD surveillance programs.29–33 The STEPS tool is a risk factor assessment instrument that gathers information at three different levels.
The first level gathers demographic and behavioral risk factor information using a questionnaire; the second collects physical measurements in a household setting; the third collects fasting blood samples for biochemical tests.34In this framework, risk factors were defined as any attribute, characteristic or exposure that would increase an individual's probability of developing a chronic NCD.
Since age, sex and consanguinity are strong confounders that are linked to other factors in the model, their effects, while included in our model, are not shown in the final graphic. We hypothesized 77 paths that directly and/or indirectly affect diabetes status.