CME INDIA Presentation by Dr. Santosh Malkani, United Diabetes and Endocrine Clinic, Nanded, Maharashtra.

(Based on a presentation at RSSDI 2023,Mumbai)

Diabetes & Shift Working - What Physicians Must Know About?

“In 2018 an a prospective study by Zhilei Shan, Yanping Li, et al showed that  both engaging in rotating night shift work and adopting an unhealthy lifestyle were found to be linked to an increased risk of type 2 diabetes. Notably, the combined risk associated with rotating night shift work and an unhealthy lifestyle surpassed the sum of risks attributed to each factor individually. These findings imply that adhering to a healthy lifestyle could potentially prevent a significant proportion of type 2 diabetes cases, with the benefits being particularly impactful for those involved in rotating night shift work.”- BMJ.

Why and where shift work?

  • Change of job pattern in India
  • Jobs in health care
  • Service and hospitality
  • Firefighting
  • Law enforcement
  • Security
  • Truck driving
  • Overtime
  • Multiple jobs
  • Side business

What is shift work?

It usually means a work activity that begins, or ends, outside of the standard daytime working hours of 7am to 7pm.

Types of Shift Work

Early mornings
Late afternoons/evenings
At the weekend
Extended work periods of 12 hours, or more
Rotating hours of work
Split shifts
On standby/on-call duties

How shift is different from routine schedule?

  • Sleep wake cycle
  • Eating habits
  • Stress
  • Transportation
  • Social and psychological
  • Addictions 
  • Family and friends

Shift work- Pathophysiology

Diabetes & Shift Working - What Physicians Must Know About?

The PER3 gene encodes the period circadian protein homolog 3 protein in humans

  • This genetic element belongs to the Period gene family and exhibits a circadian expression pattern within the suprachiasmatic nucleus, which serves as the primary circadian pacemaker in the mammalian brain.
  • Members of this gene family contribute to the regulation of circadian rhythms in locomotor activity, metabolism, and behaviour.
  • The expression of this specific gene is increased by CLOCK/ARNTL heterodimers, which is subsequently counteracted through a feedback loop involving PER/CRY heterodimers that interact with CLOCK/ARNTL.
  • Variations in this gene have been associated with sleep disorders. Numerous transcript variants, producing distinct isoforms, have been identified for this gene.


  • Broad components of health that are adversely affected by circadian misalignment due to shift work:
    • Heart health
    • Metabolic health
    • Cancer risk
    • Mental health
  • The inner circle represents biological systems that are disturbed by circadian misalignment.
  • The outer area represents broad psychosocial factors that interact with these disturbed biological systems.
  • The ring between them illustrates key medical conditions that may arise from the interaction, for which shift workers are at elevated risk.
Diabetes & Shift Working - What Physicians Must Know About?

Understanding above illustration

(Courtesy: Mason, Ivy & Qian, Jingyi & Adler, Gail & Scheer, Frank. (2020). Impact of circadian disruption on glucose metabolism: implications for type 2 diabetes. Diabetologia.)

  • The patterns of environmental light exposure are influenced by both sunlight and artificial light, with sunlight transitioning between day and night and artificial light represented as either illuminated (‘on’) or dark (‘off’).
  • The intrinsic circadian rhythms are portrayed through the endogenous clock, melatonin profiles indicating circadian day (characterized by minimal melatonin production) and circadian night (marked by increased melatonin levels under dim-light conditions).
  • The green curve illustrates the levels of endogenous melatonin during wake and sleep episodes, while behavioural rhythms are illustrated by wake and sleep periods, along with feeding patterns (depicted by a plate with a knife and fork).
  • In a modern diurnal lifestyle (a), there is a relatively harmonized alignment among daylight, artificial light, circadian day, wake periods, and meal timings.
  • It is noteworthy, however, that the sleep episode, and consequently artificial light exposure and circadian phase, tends to be delayed compared to the solar night. This delay arises from the common practice of staying awake for extended periods after sunset and often waking up after sunrise.
  • The melatonin curve demonstrates a robust rhythm synchronized with environmental and behavioural rhythms.
  • During night-shift work (b), the wake episode and meal consumption typically occur during the circadian night, accompanied by artificial lighting during the wake period. This acute misalignment results in a subdued melatonin rhythm.
  • Jet lag (c) occurs when there are rapid shifts across time zones. While sunlight and artificial light align with the wake period and meal consumption in this scenario, they are inverted compared to the circadian day-night pattern. The melatonin profile is dampened due to exposure to both sunlight and artificial light.

The impact of circadian and behavioural influences on glycaemic control and the potential transition to diabetes

  • The interplay between insulin secretion and insulin sensitivity is illustrated through two hyperbolic curves representing normoglycemia and dysglycemia.
  • As insulin sensitivity diminishes, insulin secretion intensifies to uphold normoglycemia, However, if insulin secretion proves insufficient to counteract reduced insulin sensitivity, the curve shifts downward and to the left, resulting in impaired glucose tolerance as one moves along the orange line. In this scenario, insulin secretion fails to rise adequately to offset the decline in insulin sensitivity.
  • Empirical evidence suggests that circadian misalignment, sleep restriction, and to a lesser extent, behavioural/environmental factors in the evening can compromise insulin sensitivity.
  • Beta cell function is impaired by circadian evening and recent circadian misalignment coupled with sleep restriction.
  • Glucose tolerance is adversely affected by circadian evening, circadian misalignment, significant sleep restriction, recent circadian misalignment with sleep restriction, and behavioural/environmental influences in the evening.
  • Consequently, the circadian and behavioural influences on glycaemic control can impact the transition from normoglycemia to dysglycemia, potentially contributing to the progression toward diabetes.
Diabetes & Shift Working - What Physicians Must Know About?


In 2011 Pan A, Schernhammer ES et al

  • They concluded from findings from few extensive and well-established long-term cohort studies, a favourable correlation between engaging in rotating night shift work and an elevated risk of diabetes. Additionally, an extended duration of shift work was linked to more significant weight gain.

Maria Alice Souza Schettini et al 2023 Systemic review

  • Authors found a total of 132 articles, and, after the selection process, 16 articles remained to be analysed.
  • It was observed that shift work can cause circadian misalignment and, consequently, some metabolic parameters alterations such as an impaired glycaemic control and insulin functioning, cortisol phase release, cholesterol fractions imbalance, changes in morphological indexes and melatonin secretion.

T2 Diabetes Mellitus Risk

No shift work 1.00
2yr shift work 1.05 (1.0-1.11)
20yr shift work 1.58 (1.43-1.74)

Effect on Control of Type 2 Diabetes

  • The study conducted by Manodpitipong et al. and published in the Journal of Sleep Research in December 2017 reveals an association between night-shift work and diminished glycaemic control in individuals diagnosed with Type 2 Diabetes. The research, with the PMID 28548389, suggests that night-shift work may contribute to poorer management of blood sugar levels in patients with Type 2 Diabetes.
  • In this study, participants with Type 2 Diabetes included 104 unemployed individuals, 85-day workers, and 60 night-shift workers. Various factors, such as sleep duration, sleep quality, morningness–eveningness preference, depressive symptoms, and dietary intake, were evaluated using standardized questionnaires.
  • The results indicated that night-shift workers exhibited significantly higher levels of haemoglobin A1c compared to the other groups. Specifically, there were no notable differences between day workers and unemployed participants, with median values of 7.86% versus 7.24% versus 7.09%, respectively.
  • Moreover, night-shift workers, in comparison to their counterparts, were younger, had a higher body mass index, and consumed a greater daily calorie intake. Within the group of night-shift workers, there were no significant variations in haemoglobin A1c levels based on whether they performed rotating or non-rotating shifts (P = 0.856) or had clockwise versus counter clockwise shift rotation (P = 0.833).

Effect on Control of Type 1 Diabetes

  • Managing blood sugar levels becomes challenging for diabetic individuals working shifts and during night-time due to rotating shift patterns, irregular eating habits and times, changes in physical activity, and fluctuations in natural hormone levels. Achieving optimal insulin dosing under such conditions poses a considerable challenge.
  • A study involving subjects with type 1 diabetes who worked shifts revealed a higher likelihood of having elevated HbA1c levels. This increased HbA1c poses a greater risk of long-term microvascular complications for these individuals. The findings underscore the difficulties in maintaining glycaemic control for diabetic workers in non-traditional work schedules.

Plan of Diabetes management for Shift work

  • Robust patient education
  • Eating habits
  • Sleep schedule
  • Physical activity
  • Stress and fatigue
  • Addictions
  • SMBG
  • Medication schedule

Eating habits

  • Ask to eat breakfast, lunch, and dinner at normal times as much as possible, even if person is working a late night or overnight shift.
  • Ask to avoid large meals in the middle of the night to reduce the chance of a spike in blood sugar.
  • Grabbing convenience foods or other less healthy options can be tempting when working overnight.
  • Ask to plan and prepare meals and snacks in advance
  • Ask not to rely on vending machines/ app-based food deliveries/packed food and other less healthy foods.

Sleep Schedule

  • Ask to keep track of sleep to understand patterns and how many hours sleep person is getting.
  • 7-8 hrs. sleep is good for health.
  • Ask to take short naps when not working if person is not getting enough hours of sleep.
  • Some shift workers have trouble falling asleep or staying asleep.
  • Ask to set up sleeping area so it’s dark and free from distractions.
  • Blackout curtains can create a comfortable environment to help catch up on sleep after a late-night shift.
  • Ask to avoid caffeine toward the end of shift.

Physical Activity

  • Ask make a physical activity plan that allows person to work around your shifts and sleep.
  • If the person is unable to be active on workdays, ask to focus on being active on days off.
  • Some people find that physical activity helps them sleep, while others find that it keeps them awake if done close to bedtime.
  • Pay attention to this thing before giving activity schedule.

Stress and fatigue

  • Working overnight or rotating shifts can take a toll physically, emotionally, and socially.
  • Some shift workers may feel added stress or fatigue from their unique work hours.
  • It can be more difficult to feel socially connected if work is in different hours from family and friends.
  • Ask find time for hobbies, self-care, and social time with loved ones to help manage stress.
  • Yoga and meditation may help.

Addictions- Stimulants and Sedatives

  • Shift workers often turn to stimulants such as coffee or cigarettes to keep them awake and sedatives such as alcohol or sleeping pills to help them sleep.
  • Avoid such aids as they only have short-term effects on alertness as tolerance to their effects develops.
  • Persistent use may also increase the risk of dependence.


  • Hypo and hyper are common in shift duties as lifestyle schedule keeps on changing.
  • SMBG should be done more frequently than non-shift workers.
  • Frequency should increase when the duty time changes.
  • Log of reports and symptoms along with diet schedule can help in avoiding excursions in glucose.

Drug therapy

  • Metformin unlikely to cause hypoglycemia but timing usually altered to reflect food intake.
  • Sulphonyl urea timing should match food intake.
  • SGLT 2i- Avoid dehydration.
  • DPP4i, GLP1 analogues no change.
  • Insulin:
    • Long-acting same time.
    • Short acting adjusts with carb count, SMBG and food timing.
    • Avoid premixed insulin.

Inference – Shift work can lead to

  • Metabolic syndrome
  • Obesity
  • Hypertension
  • Dyslipidaemia
  • Sleep disorders
  • Psychological issues
  • Type 2 DM
  • Prediabetes to diabetes
  • Worsening of control in both T1 and T2 DM
  • Robust patient education
  • Management:
    • Eating habits
    • Sleep schedule
    • Physical activity
    • Stress and fatigue
    • Addictions
    • SMBG
    • Medication schedule

CME INDIA learning Points

  • While the health implications of shift work have not undergone extensive scrutiny, available evidence suggests its potential influence on metabolic equilibrium, leading to conditions like obesity and other metabolic disorders.
  • Factors commonly cited in studies examining the link between night work and metabolic disorders include sleep deprivation, circadian misalignment, and alterations in dietary and physical activity behaviours.
  • Individual adaptation to night work is heavily influenced by personal factors, such as family and social commitments, yet occupational interventions can also play a positive role in easing the transition to shift work.
  • These interventions may encompass exposure to bright lights during night shifts, melatonin supplementation, maintaining shift regularity with clockwise rotation, and dietary adjustments tailored to the metabolic needs of night workers.
  • Assessing the impact of night work on health and understanding the underlying mechanisms can serve as a foundation for developing intervention strategies aimed at mitigating the health challenges associated with shift work.
  • Engaging in shift work is linked to a heightened risk of Type 2 Diabetes Mellitus (T2DM) and elevated levels of Retinol-Binding Protein 4 (RBP4). Monitoring RBP4 levels could potentially aid in the early detection of T2DM in individuals working shifts. (Ref-8)
  • Substantial evidence from large-scale studies strongly supports the association between night shift work and an increased risk of obesity. This heightened risk, in turn, strengthens the likelihood of subsequent cardiovascular events. The findings underscore the importance of recognizing the impact of night shift work on health outcomes, particularly in relation to obesity and cardiovascular health. (11)


  1. Mason, Ivy & Qian, Jingyi & Adler, Gail & Scheer, Frank. (2020). Impact of circadian disruption on glucose metabolism: implications for type 2 diabetes. Diabetologia. 63. 10.1007/s00125-019-05059-6.
  3. Schettini MAS, Passos RFDN, Koike BDV. Shift Work and Metabolic Syndrome Updates: A Systematic Review. Sleep Sci. 2023 Jul 6;16(2):237-247. doi: 10.1055/s-0043-1770798. PMID: 37425967; PMCID: PMC10325847.
  4. Pan A, Schernhammer ES, Sun Q, Hu FB. Rotating night shift work and risk of type 2 diabetes: two prospective cohort studies in women. PLoS Med. 2011 Dec;8(12):e1001141. doi: 10.1371/journal.pmed.1001141. Epub 2011 Dec 6. PMID: 22162955; PMCID: PMC3232220.
  5. Cheng WJ, Liu CS, Hu KC, Cheng YF, Karhula K, Härmä M. Night shift work and the risk of metabolic syndrome: Findings from an 8-year hospital cohort. PLoS One. 2021 Dec 13;16(12):e0261349. doi: 10.1371/journal.pone.0261349. PMID: 34898652; PMCID: PMC8668137.
  6. Bahinipati J, Sarangi R, Pathak M, Mohapatra S. Effect of night shift on development of metabolic syndrome among health care workers. J Family Med Prim Care. 2022 May;11(5):1710-1715. doi: 10.4103/jfmpc.jfmpc_375_21. Epub 2022 May 14. PMID: 35800539; PMCID: PMC9254768.
  7. Wang, L., Ma, Q., Fang, B. et al. Shift work is associated with an increased risk of type 2 diabetes and elevated RBP4 level: cross sectional analysis from the OHSPIW cohort study. BMC Public Health 23, 1139 (2023).
  8. Brum, M.C.B., Filho, F.F.D., Schnorr, C.C. et al. Shift work and its association with metabolic disorders. Diabetol Metab Syndr 7, 45 (2015).
  9. Manodpitipong A, Saetung S, Nimitphong H, Siwasaranond N, Wongphan T, Sornsiriwong C, Luckanajantachote P, Mangjit P, Keesukphan P, Crowley SJ, Hood MM, Reutrakul S. Night-shift work is associated with poorer glycaemic control in patients with type 2 diabetes. J Sleep Res. 2017 Dec;26(6):764-772. doi: 10.1111/jsr.12554. Epub 2017 May 26. PMID: 28548389.
  10. J. Young, E. Waclawski, J. A. Young, J. Spencer, Control of type 1 diabetes mellitus and shift work, Occupational Medicine, Volume 63, Issue 1, January 2013, Pages 70–72,
  11. Stefano Rizza, Massimo Federici,Night shift work, obesity and cardio-metabolic risk, Endocrine and Metabolic Science,Volume 1, Issues 3–4, 2020.

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