الفهرس 
Insulin Resistance SyndromeOnly 14 pages are availabe for public view
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Abstract
Shift work refers to non-standard work schedules that deviate from typical daytime hours. Previous evidence suggests a potential link between shift work and insulin resistance (IR). IR is characterized by a diminished response of insulin-targeted tissues to insulin. The range of metabolic disorders associated with IR extends beyond type 2 diabetes mellitus (T2DM) and encompasses dyslipidemia, hypercoagulability, hypertension, and inflammation, all of which are components of metabolic syndrome (MS). This suggests a possible connection between shift work and MS.
Assessing MS is of great importance in clinical and preventive practices. The Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) is widely used to evaluate MS. The HOMA-IR index is calculated based on fasting glucose and insulin measurements.
The objective of this study was to investigate the relationship between HOMA-IR, a marker of MS, and shift work. Additionally, a comparison was made between shift workers and non-shift workers in terms of the HOMA-IR index. Besides, a possible link between individual’s chronotype and the susceptibility for developing insulin resistance was investigated.
This study was a comparative cross-sectional design and included 60 industrial workers, who were apparently healthy, with no history of medical diseases, nor use of specific medications, and with moderate physical activity levels. Participants were classified into two groups: 30 non-shift workers and 30 shift workers based on the type of their work schedule. Data collection included personal data (name, age, date of birth, address and phone number), socio-demographic data (marital status, educational level and place of residence), occupational history (type of shift work, working hours per day, and duration of employment), lifestyle habits such as smoking, anthropometric measurements (weight, height, body mass index, waist circumference and neck circumference),family medical history of chronic diseases (hypertension, diabetes mellitus and cardiovascular diseases), nutritional behavior (number of meals per day, the type of main meal, time of night meals, number of snacks per day, types of snacks, and number of meals to be eaten outdoor per week), dietary intake assessment (using a 24-hour recall method), and the administration of the morningness-eveningness questionnaire (MEQ) to assess circadian patterns.
The total calories intake, the daily intake of energy (carbohydrates, proteins, and fats), fibers, minerals (iron, calcium, sodium, potassium, and phosphorus), and vitamins (vitamin A, vitamin C, thiamine, and riboflavin) consumed in each meal by each participant, and the mean percentage RDA of daily intake of fibers, minerals and vitamins were calculated.
Blood pressure (systolic and diastolic) was also measured and recorded in each participant and then, blood samples were collected from both groups after overnight fasting for blood analysis of fasting serum glucose levels, fasting serum insulin levels which were employed in the calculation of the HOMA-IR Index by dividing the product of fasting plasma glucose (mg/dL) and fasting plasma insulin (uIU/mL) by 405.
The results of this study indicated homogeneity between the two groups in terms of age, occupational history, most socio-demographic variables, anthropometric measurements, nutritional behavior, and dietary data. However, the frequency of eating outdoors was significantly higher in the shift workers group (p<0.05).
Regarding MEQ total scores, a highly significant difference was noticed between the two groups (p<0.001) both in MEQ total score, and scores interpretation.
In terms of laboratory results, both groups fell within the normal range values. However, the shift workers group exhibited significantly higher fasting serum insulin levels and HOMA-IR values (p<0.001) compared to the non-shift workers group. There was no significant difference in fasting serum glucose levels between the two groups.
By correlating the total scores of MEQ among the two groups with the laboratory results, there was an insignificant negative correlation between serum fasting glucose levels and MEQ score both in shift workers and non-shift workers groups. Besides, there was an insignificant negative correlation between serum fasting insulin levels and MEQ score in shift workers group, while an insignificant positive correlation was found between serum fasting insulin level and MEQ score in the non-shift workers group. Moreover, there was an insignificant negative correlation between HOMA-IR index and MEQ score in shift workers group, whereas an insignificant positive correlation was found between HOMA-IR index and MEQ score in the non-shift workers group.
Conclusion
There is a potential association between shift work (SW) and insulin resistance (IR) syndrome in male shift workers. However, this association may be underestimated due to the various types of shift work and its impacts on workers. Besides, there is a possible relationship between a subject’s chronotype and shift work.
Recommendations
• In future investigations, it is recommended to assess HOMA-IR among shift workers on a regular basis in order to follow up for the possibility of developing DM later on.
• To gain a more comprehensive understanding of the effects of shift work, it is important to take into account sleep disorders not only in shift workers but also in non-shift workers. Factors such as job strain and eating habits should be considered as potential contributors to sleep disturbances.
• When examining the association between shift work and metabolic syndrome, it is recommended to incorporate other factors of metabolic syndrome such as measuring LDL (low-density lipoprotein) and serum triglyceride levels in workers. This broader assessment can provide a more comprehensive understanding of the metabolic profile associated with shift work.
• Furthermore, it is recommended to consider the participants’ physical activity levels and their potential impact on glycemic control. This additional information can provide a more comprehensive understanding of the relationship between shift work and metabolic health.
• It is also recommended to make a future self-control study; this can be achieved by investigating the shift workers during their night shift weeks, and then reexamine the same workers during their day shift weeks and then compare the levels between them and the control group (Non-shift workers).
• It is also advisable to include a larger sample size in future studies than that used in the current study. This will enhance the generalizability and statistical power of the findings.
• Finally, it would be valuable in future studies to evaluate the potential correlation between insulin resistance and the expression of clock genes. This investigation can shed light on the underlying mechanisms linking circadian rhythms, shift work, and metabolic health.