Association between shift work and risk of type 2 diabetes mellitus: a systematic review and dose-response meta-analysis of observational studies

ABSTRACT

To evaluate the association between shift work and risk of type 2 diabetes mellitus, we searched PubMed, EMBASE and Web of Science from their inception to June 8, 2019. Observational studies examining the relationship between shift work and type 2 diabetes were included. Subgroup analyses were conducted to explore whether specific characteristics would affect the relationship. A dose-response relationship was estimated by using generalized least squares trend regression. Finally, twelve cohort studies and nine cross-sectional studies were included (inter-rater agreement, k = 0.96). The result of meta-analysis indicated that shift work was associated with an increased risk of type 2 diabetes (relative risk = 1.10, 95% confidence interval = 1.05–1.14). Subgroup analyses demonstrated that female shift workers have increased risk of type 2 diabetes while male not observed, health care workers showed the highest risk compared with civil servants and manual workers, and night shift and rotating shift were associated with an increased risk of type 2 diabetes. Dose-response meta-analysis based on three cohorts among female workers indicated that there might be a positive association between duration of shift work and the risk of type 2 diabetes. In conclusion, shift work is positively associated with an increased risk of type 2 diabetes. Among female workers, with the years of exposure to shift work prolonged, the risk of type 2 diabetes might increase accordingly. In the future, more studies are needed to confirm the results of dose-response analysis.

KEYWORDS:

• Type 2 diabetes mellitus
• dose-response
• meta-analysis
• shift work

Disclosure of interest

The authors report no conflict of interest.

Electrical search strategy

PubMed

#1 work schedule tolerance [MeSH]

#2 shift work schedule [MeSH]

#3 night shift* OR morning shift* OR evening shift* OR afternoon shift* OR shift work OR shiftwork* OR shift worker* OR shift working OR work shift* OR rotating shift* OR shift combination* OR shift duration OR shift length OR shift system* OR shift rotation OR shift roster* OR extended shifts OR extended work shifts OR night work OR evening work OR shift schedule* OR work schedule* OR irregular working hours OR atypical work OR two shift OR three shift OR light at night OR work at night

#4 #1 OR #2 OR #3

#5 diabetes mellitus [MeSH]

#6 insulin resistance [MeSH]

#7 diabet* OR insulin resistance OR impaired glucose toleranc* OR IGT OR glucose intoleranc* OR glucose metabolism OR fasting plasma glucose OR FPG OR fasting glucose OR fasting blood glucose OR fasting plasma sugar OR IFG OR prediabet* OR hyperglycemia MODY OR NIDDM OR T2DM OR T2D OR DM OR hemoglobin A1c OR HbA1C

#8 #5 OR #6 OR #7

#9 #4 AND #8

EMBASE

#1 ‘work schedule’/exp

#2 ‘shift worker’/exp

#3 ‘shift work’/exp

#4 (‘night shift*’ OR ‘morning shift*’ OR ‘evening shift*’ OR ‘afternoon shift*’ OR ‘shift work’ OR shiftwork* OR ‘shift worker*’ OR ‘shift working’ OR ‘work shift*’ OR ‘rotating shift*’ OR ‘shift combination*’ OR ‘shift duration’ OR ‘shift length’ OR ‘shift system*’ OR ‘shift rotation’ OR ‘shift roster*’ OR ‘extended shifts’ OR ‘extended work shifts’ OR ‘night work’ OR ‘evening work’ OR ‘shift schedule*’ OR ‘work schedule*’ OR ‘irregular working hours’ OR ‘atypical work’ OR ‘two shift’ OR ‘three shift’ OR ‘light at night’ OR ‘work at night’)/ti;ab

#5 #1 OR #2 OR #3 OR #4

#6 ‘diabetes mellitus’/exp

#7 ‘insulin resistance’/exp

#8 (diabet* OR ‘insulin resistance’ OR ‘impaired glucose toleranc*’ OR IGT OR ‘glucose intoleranc*’ OR ‘glucose metabolism’ OR ‘fasting plasma glucose’ OR FPG OR ‘fasting glucose’ OR ‘fasting blood glucose’ OR ‘fasting plasma sugar’ OR IFG OR prediabet* OR hyperglycemia MODY OR NIDDM OR T2DM OR T2D OR DM OR ‘hemoglobin A1c’ OR HbA1C)/ti;ab

#9 #6 OR #7 OR #8

#10 #5 AND #9

Web of Science

#1 TS=(‘night shift*’ OR ‘morning shift*’ OR ‘evening shift*’ OR ‘afternoon shift*’ OR ‘shift work’ OR shiftwork* OR ‘shift worker*’ OR ‘shift working’ OR ‘work shift*’ OR ‘rotating shift*’ OR ‘shift combination*’ OR ‘shift duration’ OR ‘shift length’ OR ‘shift system*’ OR ‘shift rotation’ OR ‘shift roster*’ OR ‘extended shifts’ OR ‘extended work shifts’ OR ‘night work’ OR ‘evening work’ OR ‘shift schedule*’ OR ‘work schedule*’ OR ‘irregular working hours’ OR ‘atypical work’ OR ‘two shift’ OR ‘three shift’ OR ‘light at night’ OR ‘work at night’)

#2 TS=(diabet* OR ‘insulin resistance’ OR ‘impaired glucose toleranc*’ OR IGT OR ‘glucose intoleranc*’ OR ‘glucose metabolism’ OR ‘fasting plasma glucose’ OR FPG OR ‘fasting glucose’ OR ‘fasting blood glucose’ OR ‘fasting plasma sugar’ OR IFG OR prediabet* OR hyperglycemia MODY OR NIDDM OR T2DM OR T2D OR DM OR ‘hemoglobin A1c’ OR HbA1C)

#3 #1 AND #2