**2. Epidemiological arguments**

An impressive number of studies have emphasized that risk factors for cardiovascular and diabetes are more prevalent in low‐educated, low‐income population [3–8], particularly related to the high incidence of the negative health habits (smoking, drinking, high fat or low fruit diet [8]). Being a member of a low social class during childhood [9] also favoured unhealthy‐related behaviours: low level of sport practice, high fat diet, emotional stress and material unfavourable conditions. In different cohorts, significant differences between men and women [6, 7] were found, which could not be fully explained by sexual level of hormones. Marital status [5] in men appeared to have different influences in developing countries com‐ pared to the developed ones: a high risk factor in developing countries and a low risk factor in western countries [4]. The high prevalence in developing countries has been explained by cultural habits such as accessibility to eat out or practice outdoor physical activities and less concern about gaining weight. In women, marital status in western countries is associated with an increased risk.

enhances vascular endothelium vasoconstriction and inflammation—promoting atherosclero‐ sis and induces a systemic low grade metabolic inflammation. Two are the major clinical con‐ sequences of the IR: the cardio‐vascular disease and diabetes. There are also significant links between IR and other clinical conditions such as non‐alcoholic fatty liver disease, polycystic ovary syndrome and colorectal cancer. Cardiovascular diseases are already the leading cause of death in industrialized countries [1] and diabetes prevalence has doubled between 1980 and 2014. Diabetes is estimated to become the seventh leading cause of death in 2030 [2]. Taken together, all medical conditions related to IR are responsible for a high percentage of the total mortality rate. Therefore, prevention and early diagnosis is a major public health topic.

For many years, IR has been considered a complication of obesity but a non‐obese metabolic obese profile has been identified in the past few years, as up to 15–30% of the IR subjects are in the normal range value of the BMI. The complex pathogeny of IR has been explained by complementary or synergic interactions between genetic and epigenetic factors, gut microbiota and environmental factors. As the environmental factors are the modifiable ones, the interven‐ tion, including workplace interventions, became nowadays a major health prevention direction.

Insulin resistance is difficult to measure in clinical practice; therefore, surrogates are used for its assessment such as basal insulinemia, the homeostasis assessment index (HOMA‐IR), glucose ratio to insulin and the glucose tolerance test. Clinical markers for IR are lipid metab‐ olism impairment (increased triglycerides, reduced HDL cholesterol and increased LDL cholesterol), plasma uric acid increase, renal disease markers (albuminuria) and cardiovas‐ cular effects (hypertension and cardiac remodelling). As already mentioned, obesity, particu‐ larly the visceral deposition of the adipose tissue, is a risk factor. In different configurations, according to different scientific organizations, these factors define the metabolic syndrome, a more suitable clinical diagnostic. Although I fundamentally agree with those considering that metabolic syndrome is an 'artificial syndrome'—in fact is just a cluster of risk factors—and that diagnostic procedures should be developed for an easier clinical diagnostic of the IR syndrome, this article will have to rely on data accumulated under the metabolic syndrome

Nutrition, lack of physical exercise are not occupational hazards that are traditionally IR risk factors. In recent research, there is more and more evidence accumulated on how particular occu‐ pational risks are involved in IR and this makes the subject of increasing interest for occupational

An impressive number of studies have emphasized that risk factors for cardiovascular and diabetes are more prevalent in low‐educated, low‐income population [3–8], particularly related to the high incidence of the negative health habits (smoking, drinking, high fat or low fruit diet [8]). Being a member of a low social class during childhood [9] also favoured unhealthy‐related behaviours: low level of sport practice, high fat diet, emotional stress and material unfavourable conditions. In different cohorts, significant differences between men

entity, as it is much more frequently used in the medical literature.

physicians.

104 Occupational Health

**2. Epidemiological arguments**

In the early years of socio‐economic development, the changing habits represent a risk fac‐ tor for IR [10, 11]. The theory of epidemiological transition states that, under development conditions, there is a switch between mortality dominated by infectious diseases to mortality related to degenerative and man‐made diseases [12]; conditions related to IR fill in this cat‐ egory, reflecting changes in nutrition and transition from physical activity to sedentariness [11]. In these countries, at the beginning of the development era, the high income class has higher risk [5], as it has access to more resources, moves to more sedentary lifestyle and tries to compensate all childhood economical disadvantages and frustrations accumulated.

Even if there are differences according to the socio‐economic development period the country is passing by, there are also many similarities. For example, a comparison between Taiwan and US revealed interesting similar inflammation scores (serum IL‐6, CRP, fibrinogen, sICAM‐1, sE‐selectin and sIL‐6R), cardiovascular risk factors (systolic and diastolic blood pressure, total cholesterol, HDL cholesterol, triglycerides, glycosylated haemoglobin, BMI, waist‐hip ratio and resting pulse) and hypothalamic‐pituitary‐adrenal axis and sympathetic nervous system function (epinephrine, norepinephrine, DHEAS and urinary cortisol) in relation to the socio‐ economic status [13].

*Occupation and employment status* are major determinants of the economical welfare and unem‐ ployment has been linked to metabolic risk in both developed and in under development countries [4, 5, 14]. There is difficult to find common grounds for data reported from different countries, as occupations are differently coded and registered: an US countrywide survey found maximum incidence of risk factors in the farm industry (operators, managers and supervisors), in food preparation and food services, motor vehicle operators and among administrative staff (secretaries, stenographers and typists), and the lowest in professional specialties (particularly in writers, artists, entertainers and athletes) [15]. Several studies have classified occupations in manual (blue collars) and non‐manual (white collars, office workers) activities and found either increased or a decreased incidence of metabolic syndrome components in manual workers [16, 17]. These differences were most probably related to the confounders not included in these stud‐ ies, such as nutrition, smoking, alcohol and level of occupational physical activity.

There are many limitations of these epidemiological studies for a direct application in the occupational physician practice, although the prevalence and social risk factors are important. They give a broader perspective for any intervention proposed. The epidemiological transi‐ tions reflect the major trends and do not provide specific information by industry. As far as working conditions are concerned in the transitional period, the main negative factors are the unbalanced working hours to leisure activities, the increased number of jobs with sedentary activity and the increased amount of perceived stress.
