Table 3.
Climate factors and glucose related outcomes study table
| Author, Year | Study size & location | Study Characteristics | Age range or Mean ± SD | Exposure measures | Outcome measures | Model covariates | Main Findings |
|---|---|---|---|---|---|---|---|
| Meek, 2020 [37] | n = 23,375, United Kingdom | Cohort: enrolled pregnant women with singleton pregnancies from 1/2004 to 12/2008 | 30.7 ± 5.6 years | Season: day of delivery | Random plasma glucose, Measured at enrollment (11–16 weeks) | Maternal age, BMI, parity, ethnicity | •Random plasma glucose levels varied significantly by season (p < 0.001) and were highest in spring (Mar-Apr) and lowest in fall (Aug-Sept) |
| Molina-Vega, 2020 [38] | n = 2366, Malaga, Spain | Cohort: retrospective cohort of women referred to a Pregnancy and Diabetes clinic for GDM screening | 32 ± 5.2 years |
A) Ambient temperature: 1) mean ∆ temp 2) mean temp Day of OGTT, 14 days pre-OGTT, and 28 days pre-OGTT B) Season Winter (Dec 21st – Mar 20th) Spring (Mar 21st – Jun 20th) Summer (Jun 21st – Sep 20th) Autumn (Sep 21st – Dec 20th) |
Glucose levels (OGTT) A) continuousB) abnormal (NDDG cut offs) Two-step: 1) 50 g GLT 2) 100 g OGTT |
Maternal age |
•Odds of abnormal 1-, 2-, and 3-h OGTT glucose levels were significantly higher in summer compared to autumn (e.g. 2 h OGTT glucose: OR 1.8, 95% CI: 1.4–2.4) •Mean temperature on the day of the OGTT was negatively correlated with fasting glucose (r = − 0.08) but positively correlated with 1-, 2-, and 3-h OGTT glucose levels |
| Petry, 2019 [39] | n = 1074 Cambridge, United Kingdom | Cohort: Cambridge Baby Growth Study, enrolled pregnant women during early pregnancy between 4/2001–3/2009 | 33.4 years | Season: Winter (Dec-Feb) Spring (Mar-May) Summer (Jun-Aug) Autumn (Sep-Nov) |
1) Glucose levels (OGTT) 2) HOMA S & HOMA B 75 g OGTT at median 28.4 weeks |
•Season of OGTT was not associated with OGTT glucose levels •Season of OGTT was not associated with HOMA S or HOMA B |
|
| Shen, 2019 [40] | n = 2120, Brisbane & Newcastle, Australia | Cohort: Women enrolled at Australian sites of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) from 2001 to 2006 | 29.6 ± 5.4 years |
A) Season: Winter (Jun-Aug) Spring (Sep-Nov) Summer (Dec-Feb) Autumn (Mar-May) B) Ambient temperature (°C): Mean monthly temp |
A) Glucose levels (OGTT) B) HbA1C C) HOMA-IR, 75 g OGTT at 24–36 weeks |
•Mean fasting glucose, HbA1c, and HOMA-IR levels were lowest in the summer and highest in the winter months •Mean 1 and 2-h OGTT glucose levels were highest in the summer and lowest in the winter •Fasting glucose (r = − 0.145) and HbA1c (r = − 0.069) were negatively correlated with mean monthly temperature •1 h and 2 h OGTT glucose levels were positively correlated with mean monthly temperatures (r = 0.079 and r = 0.093, respectively) |
|
| Wainstock, 2019 [33] | n = 59,882, Israel | Retrospective cohort: Included all pregnant women who underwent a GCT from 2005 to 2016 at Central District of Clalit Health Services in Israel. | 29.5 ± 51 years | Seasons: Winter (Nov-Mar) Spring (April–May Summer (June-Aug) Autumn (Sept-Oct) Combined: Hot season (summer & spring) Cold season (fall & winter) |
1) Glucose levels (GCT & OGTT) 2) Abnormal GCT 3) Abnormal OGTT Thresholds: Carpenter and Coustan 50-g GCT & 100-g OGTT |
Maternal age and BMI |
•Mean GCT glucose levels and incidence of abnormal GCT varied by season – lowest in winter, followed by spring, fall, and summer •GCTs performed in the winter had the lowest risk of being abnormal (e.g. OR 1.58, 95%CI 1.51. 1.66, for GCT in summer compared to winter) •No significant difference in rate of abnormal OGTT between seasons •Results were similar when comparing warm and cold seasons |
| Retnakaran, 2018 [41] | n = 1464, Toronto, Canada | Cohort: enrolled pregnant women at time of GDM screening | 34 ± 4 years |
Ambient temperature (°C): 1) mean temp 2) daily temp change. Mean temperature: day of OGTT, 7, 14, 21, 28, 35, 42, 49, 56 days pre-OGTT. Temperature ∆: daily difference between min and max temp on OGTT day and average ∆ 7, 14, 21, 28, 35, 42, 49, 56 days pre-OGTT |
1) Glucose levels (OGTT) 2) Insulin resistance (Matsuda index & HOMA-IR) 3) Beta cell function (ISSI-2 & (IGI)/HOMA-IR) 100-g OGTT in late 2nd trimester |
Maternal age, ethnicity, FH of diabetes, pp-BMI, GWG through OGTT, week gestation at time of OGTT |
•In covariate-adjusted models, temperature ∆ in the pre-OGTT periods (14, 21, 28, 35, 42, 49, 56 days) were positively associated with blood glucose (OGTT fasting glucose & AUCglucose) •Temperature ∆ in the pre-OGTT periods (7, 14, 21, 28, 35, 42, 49, 56 days) were inversely associated with ISSI-2 and IGI/HOMA-IR •Mean temperature in the weeks preceding OGTT were suggestively associated with higher OGTT fasting glucose and AUGglucose •Stratified by season: temperature ∆ associated with increased OGTT fasting glucose (e.g. 28 days pre OGTT: β 0.07, p = 0.001), AUCglucose, and decreased beta cell function, in season where daily temperature is increasing (February – July) Mean temperature associated with increased OGTT fasting glucose (e.g. 28 days pre OGTT: β 0.039, p = 0.04), AUCglucose and suggestively decreased beta cell function, only in February–July |
| Vasileiou, 2018 [27] |
A) n = 7618 B) n = 768, Athens, Greece |
Two cohorts: A) Retrospective cohort: 7618 pregnant women who underwent a 100 g OGTT from 2002 to 2012. B) Prospective cohort: 768 pregnant women enrolled in 3rd trimester followed over 18-month period from 1/2013 to 6/2014. |
Not provided |
A) Season B) Ambient Temperature: 1) Mean monthly temperature 2) Daily temperature (9 am) Three temp groups: 1) < 24.9 °C 2) 25–29.9 °C 3) > 30 °C |
Glucose levels (OGTT) Study A: 100 g OGTT in third trimester Study B: 75 g OGTT in third trimester | Maternal age, gestational age, BMI, GWG, blood pressure |
Study A: •Blood glucose levels at 1, 2, 3 h differed significantly by season – highest in summer and lowest in winter Study B: •Temperature was positively associated with 1 h glucose levels •Daily temperature > 25 °C was associated with increased risk of abnormal 1 h glucose levels (RR 2.2, 95% CI 1.5, 3.3) •1 h and 2 h glucose levels were significantly higher in > 30 °C daily temperature group |
| Chiefari, 2017 [42] | n = 5473 Calabria, Italy | Cohort: Study population formed based on women who underwent an OGTT for GDM screening at a hospital in Calabria, Italy from 8/2011 to 12/2016. | 33 (29–36) years | Seasons: Fall, Winter, Spring Summer, Warm half & cold half of the year, 24-h average temperature each month | Glucose levels (OGTT) 75 g OGTT at 16–18 or 24–28 weeks | Maternal age, ppBMI, prior GDM, FH of diabetes |
•Mean 1 h and 2 h glucose levels were highest in summer (1 h, 144; 2 h, 115) compared to other seasons •Fasting glucose levels did not vary by season •Higher 24-h average monthly temperature was associated with increased 1 h and 2 h glucose levels, but not fasting levels |
| Katsarou, 2016 [25] | n = 11,538, Skane county, Sweden | Cohort: Mamma Study, recruited women from 4 obstetric delivery departments in Skane county, Sweden from 2003 to 2005. | 29.9 ± 5.1 years | Seasons: Winter (Dec-Feb) Spring (Mar-May) Summer (June-Aug) Fall (Sept-Nov) Mean monthly ambient temperature | Glucose levels (OGTT) 75 g OGTT at 28 weeks (capillary plasma glucose) | Maternal age |
•Mean monthly temperature was positively associated with 2 h glucose levels, e.g. 0.009 mmol/L increase in glucose per degree (p < 0.001) •OGTT during summer was associated with increased 2 h glucose levels |
| Moses, 2016 [45] | n = 7343, Wollongong, Australia | Cohort: pregnant women with OGTT medical record data from 2012 to 2014, from public and private pathology labs in the Wollongong, Australia area. | Not provided | Seasons: Summer (Dec-Feb) Fall, Winter, Spring | Glucose levels (OGTT) 75 g OGTT at 24–28 weeks, Thresholds: Modified WHO (2006) | Unadjusted |
•1 h and 2 h blood glucose were significantly lower in winter compared to the overall mean levels (p < 0.0001) •Glucose mmol/L), median (IQR) Winter: 1 h 6.7 (5.0–7.8); 2 h 5.6 (4.8–6.6) Overall: 1 h 6.9 (5.9–8.1); 2 h 5.8 (5.0–6.7) |
| Janghorbani, 2006 [46] | n = 4852, Plymouth, United Kingdom | Cohort: study population based on pregnant women in Plymouth, UK screened for GDM from 1/1996 to12/1997 using data from Plymouth Child Health Database and laboratory and midwifery notes. | GDM: 30.9 ± 5.5 years, Non-GDM: 28.1 ± 5.4 years | Month and season | Glucose levels (OGTT & random plasma glucose) Random plasma glucose followed by 75 g OGTT at 26–28 weeks | Maternal age, birthweight, gestational age |
•In covariate-adjusted models, month and season were not associated with glucose levels •OGTT glucose levels did not vary significantly by month or season |
| Moses, 1995 [26] | n = 2749, Wollongong, Australia | Cohort: study population based on women with available OGTT data collected from clinics and obstetric offices from 1/1993 to 6/1994. | 27 ± 5.1 years | Month & Season: Summer, Fall, Winter, Spring. Mean monthly ambient temperature (9 am) | Glucose levels (OGTT) 75 g OGTT at mean 28 weeks | Maternal age, parity, BMI, week of testing |
•Mean monthly temperature was positively associated with 2 h glucose levels (β 0.026 mmol− 1, p = 0.01) •2 h glucose levels differed significantly by season – highest in summer and lowest in winter (p = 0.011) |
| Schmidt, 1994 [47] | n = 1030, Porto Alegre, Brazil | Cohort: study subjects were women 20+ years receiving prenatal care at two university hospitals with OGTT results during 24–28 weeks gestation from 7/1991 to 3/1993. | 20–45 years | Daily ambient temperature (9 am) |
1) Glucose levels (OGTT) 2) Abnormal OGTT (≥7.8 mmol/L, 2 h) 75 g OGTT at 24–28 weeks |
Maternal age and BMI at enrollment |
•Frequency of abnormal glucose tolerance was positively associated with temperature (e.g. 10% at 20–24° vs. 4.9% at 15–19 °C) •1 h and 2 h glucose levels were positively associated with daily temperature (0.07 mmol/L per degree increase in temperature) |
Abbreviations: GCT glucose challenge test, OGTT oral glucose challenge test, GDM gestational diabetes mellitus, HOMA-IR homeostatic model assessment for insulin resistance, ISSI-2 insulin sensitivity index-2, IGI insulinogenic index, AUCglucose area under the glucose response curve, WHO World Health Organization, BMI body mass index