Gestational diabetes mellitus and retinal microvasculature

Exploring the effect of gestational diabetes mellitus on retinal vascular morphology by PKSEA-Net

Background

Gestational diabetes mellitus (GDM) is a temporary metabolic disorder in which small retinal vessels may have experience subtle changes before clinical lesions of the fundus retina appear. An innovative artificial intelligence image processing technology was applied to locate and analyze the small retinal vessel morphology and accurately evaluate the changes of the small retinal vessels in GDM patients and pregnant women with normal blood glucose and non-pregnant women with normal blood glucose.

Methods

The subjects were divided into three groups:GDM group, pregnant control group (PC), and normal control group (NC). Use optical coherence tomography angiography (OCTA) to collect OCT images of subjects,and perform quantitative identification and analysis of retinal vessel parameters based on artificial intelligence measurement software integrated the prior knowledge supervised edge-aware multi-task network (PKSEA-Net): Retinal arteriolar lumen diameter (RALD), retinal arteriolar outer diameter (RAOD), retinal venular lumen diameter (RVLD),retinal venular outer diameter (RVOD),arterial wall thickness (AWT),venular wall thickness (VWT),arterial wall to lumen ratio (AWLR),venular wall to lumen ratio (VWLR),arterial wall cross-sectional area (AWCSA),venular wall cross-sectional area (VWCSA), arteriovenous ratio (AVR).

Results

This study revealed significant differences in RVOD, RVLD, VWT, VWCSA and AVR between the GDM group and the PC group (p = 0.005, p < 0.027, p = 0.008, p = 0.001, p = 0.022), significant differences in RVOD, RVLD, VWT, VWCSA and AVR between the GDM group and the NC group (p < 0.001, p = 0.001, p < 0.001, p < 0.001, p = 0.001). In GDM group, RVOD, RVLD, VWT and VWCSA increased, while AVR decreased. There were no significant differences in RVOD, RVLD, VWT, VWCSA and AVR between PC group and NC group (p = 0.139, p = 0.263, p = 0.107, p = 0.059, p = 0.218), and no significant differences in VWLR among the three groups (p > 0.05). No significant difference was observed in retinal artery vascular parameters (RAOD, RALD, AWT, AWLR, AWCSA) across the three groups (p > 0.05).

Conclusion

There were increases in RVOD, RVLD, VWT, and VWCSA, decrease in AVR in patients with GDM. However, no significant difference of retinal vascular parameters was shown between normal pregnant women and normal non-pregnant women. PKSEA-Net can assist to identify changes in retinal vascular morphology and diagnose micro-vascular lesion early in normal pregnant women and high-risk groups of GDM.

Utility of Fundus Autofluorescence and Optical Coherence Tomography in Measuring Retinal Vascular Thickness, Macular Density, and Ophthalmic Manifestations in Women with Gestational Diabetes Mellitus

Background: Gestational diabetes mellitus (GDM) is a transient elevation of blood glucose during pregnancy. It is typically not associated with diabetic retinopathy. However, certain investigators revealed retinal microvascular injury. In this study, we aimed to assess the ophthalmic findings, optical coherence tomography (OCT) parameters, and retinal vascular thickness and macular density through fundus autofluorescence (FAF). Methods: Prospectively, women diagnosed with GDM were enrolled in this study. All the participants underwent comprehensive ophthalmic examination. Furthermore, macular OCT with analysis of the central subfield thickness (CST) and total thickness was carried out. Moreover, FAF was performed, and the macular density and retinal vascular thickness were extracted using ImageJ software. Results: Thirty-four women were enrolled. The mean maternal age was 32.7 years. No participant had diabetic retinopathy, nine eyes had early cataract, and two eyes had keratoconus. Higher levels for the 1 h oral glucose tolerance test (OGTT) were associated with a drop in the CST and total thickness. Moreover, women who underwent CS had higher levels of total thickness. Higher levels for the fasting OGTT were associated with a thinner inferior temporal retinal artery. Pregnant women with miscarriages had lower macular density on FAF, as represented by lower values of integrated density and mean gray values. Higher levels for the fasting OGTT were associated with higher values of integrated density. Conclusions: Although GDM is typically not associated with diabetic retinopathy, microscopic changes involving the microvascular environment and the macula may occur. Regular ophthalmic screening for women with GDM may be advised. Larger studies with more investigations may reveal further findings.

A Novel Method for the Measurement of Retinal Arteriolar Bifurcation

INTRODUCTION

The purpose of this research was to develop protocols for evaluating the bifurcation parameters of retinal arteriole and establish a reference range of normal values.

METHODS

In this retrospective study, we measured a total of 1314 retinal arteriolar bifurcations from 100 fundus photographs. We selected 200 from these bifurcations for testing inter-measurer and inter-method agreement. Additionally, we calculated the normal reference range for retinal arteriolar bifurcation parameters and analyzed the effects of gender, age, and anatomical features on retinal arteriolar bifurcation.

RESULTS

The measurement method proposed in this study has demonstrated nearly perfect consistency among different measurers, with interclass correlation coefficient (ICC) for all bifurcation parameters of retinal arteriole exceeding 0.95. Among healthy individuals, the retinal arteriolar caliber was narrowest in young adults and increased in children, teenagers, and the elderly; retinal arteriolar caliber was greater in females than in males; and the diameter of the inferior temporal branch exceeded that of the superior temporal branch. The angle between the two branches of retinal arteriolar bifurcation was also greater in females than in males. When using the center of the optic disc as a reference point, the angle between the two branches of the retinal arteriole at the proximal or distal ends increased. In contrast, the estimated optimum theoretical values of retinal arteriolar bifurcation were not affected by these factors.

CONCLUSIONS

The method for the measurement of retinal arteriolar bifurcation in this study was highly accurate and reproducible. The diameter and branching angle of the retinal arteriolar bifurcation were more susceptible to the influence of gender, age, and anatomical features. In comparison, the estimated optimum theoretical values of retinal arteriolar bifurcation were relatively stable. Video available for this article.

Relationship Between Disease and Treatment Factors in Diabetes With Vision Difficulty: A Cross-Sectional, Population-Based Analysis

BACKGROUND AND OBJECTIVE

Relationships between disease and treatment factors of diabetes and vision difficulty remain largely unknown. This study investigated the relationship between disease and treatment factors in diabetes and participants' self-reported vision difficulty.

PATIENTS AND METHODS

This was a cross-sectional, population-based analysis. Data from the National Health Interview Survey was used and analyzed through univariable and multivariable logistic regression.

RESULTS

From the 29,464 included participants, logistic regression showed increased odds of self-reported vision difficulty among participants with diabetes (odds ratio [OR] = 2.14, P < 0.001), prediabetes (OR = 1.95, P < 0.001), or gestational diabetes (OR = 1.54, P < 0.001) compared to participants without diabetes. Those who reported having diabetes for more than a year had higher odds of vision difficulty (OR = 1.97, P = 0.02), as did those who were taking insulin (OR = 1.62, P < 0.001), those who had taken less insulin to save money within the past year (OR = 1.87, P = 0.01), and those who reported experiencing diabetes-related stress (OR = 2.14, P < 0.001).

CONCLUSIONS

Duration of diabetes, diabetes-related stress, and taking less insulin than recommended to save money were associated with vision difficulty. [Ophthalmic Surg Lasers Imaging Retina 2024;55:142-153.].

Preconception maternal retinal arteriolar narrowing and fetal growth throughout pregnancy: A prospective cohort study

OBJECTIVE

To investigate the association between preconception maternal retinal arteriolar calibre and fetal growth.

DESIGN, SETTING AND POPULATION

A hospital-based, prospective preconception cohort including 369 women with a singleton live birth.

METHODS

We collected detailed information on sociodemographic status, pregnancy history and lifestyle, and performed retinal imaging at the preconception visit.

MAIN OUTCOME MEASURES

We retrieved medical records documenting fetal growth biometrics (e.g., abdominal circumference [AC], head circumference [HC], femur length [FL]) at 11-13, 18-21, 24-28, and 32-34 weeks throughout pregnancy. We then computed the z scores for all fetal growth biometrics from 14 weeks of gestation where data were available, referencing the INTERGROWTH-21st fetal growth chart. We used a linear mixed model to estimate the association between maternal preconception retinal arteriolar calibre and fetal growth biometrics z scores throughout pregnancy, with random intercept accounting for repeated measures within individuals. We then performed a multivariable linear regression of maternal preconception retinal arteriolar calibre and z score changes for all fetal growth biometrics between 24-28 weeks and 32-34 weeks of gestation, after full adjustment.

RESULTS

Maternal preconception generalised retinal arteriolar narrowing was consistently associated with a reduction in fetal AC z scores (-0.34; 95% CI -0.66 to -0.03) throughout pregnancy. In addition, women with preconception generalised retinal arteriolar narrowing tended to have significantly reduced z score changes in AC (-0.41; 95% CI -0.90 to -0.001) and fetal FL (-0.55; 95% CI -1.00 to -0.10) between 24-28 weeks and 32-34 weeks of gestation, respectively.

CONCLUSIONS

Our findings suggest that women with narrower preconception retinal arterioles had smaller fetuses, evidenced by reductions in AC and FL z score throughout pregnancy.

Nutrition interventions and clinical outcomes of pregnant women with gestational diabetes mellitus: More than meets the eye

In the retrospective study by Luo et al regarding clinical outcomes in gestational diabetes mellitus (GDM), the results are statistically significant in favour of the benefits of individualized nutrition interventions enumerated therein. The study has provided important evidence to improve maternal and child health in the Asian population. The methods, however, appear to have considerable limi-tations, wherein the time point of diagnosis of GDM, severity of GDM, selection bias, compliance to therapy, important maternal covariates, observable microvascular abnormalities and the confounding effect of added insulin have not been considered. We have provided suggestions to improve the external validity of the study, including the use of Equator Network reporting guidelines and inclusion of overweight and obese patients in future studies.

Preconception maternal retinal venular widening and steeper resistance increments in the utero-fetoplacental circulation in pregnancy

We investigated the relationship of preconception maternal retinal vasculature and utero-fetoplacental circulation in ensuing pregnancy. Embedded in a hospital-based, prospective preconception cohort, 396 women with a singleton live birth were included for analysis. We assessed retinal vascular caliber during preconception phase and retrieved ultrasonogram results documenting utero-fetoplacental circulatory indices using Doppler ultrasonography and documented them at 18-21 weeks, 24-28 weeks, and 32-34 weeks where available. We performed a modified Poisson regression to estimate the relative risk of utero-fetoplacental abnormalities, adjusting for major confounders including pre-pregnancy and blood pressure. Per 10 μm increment in maternal preconception retinal venules was associated with over two-fold risks in developing notching (Relative risk [RR]: 2.84; 95% confidence interval [CI]: 1.79, 4.81) and ≥95th percentile umbilical artery pulsatility index (2.36; 1.72, 3.23) during mid-to-late pregnancy, respectively. Women with preconception retinal venular widening tended to demonstrate steeper resistance increments in both maternal uterine arteries and fetal umbilical arteries during mid-to-late pregnancy.

Maternal glycemic status during pregnancy and mid-childhood plasma amino acid profiles: findings from a multi-ethnic Asian birth cohort

BACKGROUND

Increasing maternal glycaemia across the continuum during pregnancy may predispose offspring to subsequent cardiometabolic risk later in life. However, evidence of long-term impacts of maternal glycemic status on offspring amino acid (AA) profiles is scarce. We aimed to investigate the association between maternal antenatal glycaemia and offspring mid-childhood amino acid (AA) profiles, which are emerging cardiometabolic biomarkers.

METHODS

Data were drawn from the Growing Up in Singapore Towards healthy Outcomes (GUSTO) study, a multi-ethnic Asian birth cohort. A subset of 422 mother-child dyads from the GUSTO study, who was followed from early pregnancy to mid-childhood, was included. Mothers underwent an oral glucose tolerance test (OGTT) at 26-28 weeks gestation, with fasting and 2-h plasma glucose concentrations measured and gestational diabetes mellitus (GDM) diagnosed per WHO 1999 guidelines. Offspring fasting plasma samples were collected at mean age 6.1 years, from which AA profiles of nine AAs, alanine, glutamine, glycine, histidine, isoleucine, leucine, valine, phenylalanine, and tyrosine were measured. Total branched-chain amino acids (BCAAs) were calculated as the sum of isoleucine, leucine, and valine concentrations. Multi-variable linear regression was used to estimate the association of maternal glycemic status and offspring mid-childhood AA profiles adjusting for maternal age, ethnicity, maternal education, parity, family history of diabetes, ppBMI, child sex, age and BMI z-scores.

RESULTS

Approximately 20% of mothers were diagnosed with GDM. Increasing maternal fasting glucose was significantly associated with higher offspring plasma valine and total BCAAs, whereas higher 2-h glucose was significantly associated with higher histidine, isoleucine, valine, and total BCAAs. Offspring born to mothers with GDM had higher valine (standardized mean difference 0.27 SD; 95% CI: 0.01, 0.52), leucine (0.28 SD; 0.02, 0.53), and total BCAAs (0.26 SD; 0.01, 0.52) than their counterparts. Inconsistent associations were found between maternal GDM and other amino acids among offspring during mid-childhood.

CONCLUSIONS

Increasing maternal fasting and post-OGTT glucose concentrations at 26-28 weeks gestation were significantly associated with mid-childhood individual and total BCAAs concentrations. The findings suggest that elevated maternal glycaemia throughout pregnancy, especially GDM, may have persistent programming effects on offspring AA metabolism which were strongly associated with adverse cardiometabolic profiles at mid-childhood.

Assessment of Visual Evoked Potential to Detect Visual Pathway Dysfunction in Gestational Diabetes Mellitus: A Longitudinal Case-Control Study With Postpartum Follow-up

BACKGROUND

The increasing prevalence of gestational diabetes mellitus (GDM) during pregnancy has opened the opportunity to study its short- and long-term effects on maternal ophthalmic health. Visual evoked potential (VEP) is a non-invasive electrophysiological test that detects functional disturbances along the visual pathway before the physical signs of diabetic retinopathy (DR) can set in. This longitudinal study is aimed at the assessment of changes in VEP in GDM during different stages of pregnancy and 6-12 weeks after parturition by comparing it with normoglycemic controls.

DESIGN AND METHOD

Diagnosed cases of GDM were recruited along with normoglycemic controls at 24-28 weeks of gestation. Each participant was required to attend two follow-up appointments at 32-38 weeks of gestation and 6-12 weeks after parturition. A blood sample was taken in a fasting state to record biochemical parameters. VEP was recorded using Neuropack S1 MEB-9400 electrodiagnostic equipment (Nihon Kohden, Tokyo, Japan) in a dark room by providing pattern reversal stimuli to each eye.

RESULTS

A total of 29 participants (15 in the control group and 14 in the GDM group) completed the entire study procedure. The observed mean P100 latency of both eyes in the GDM group was recorded longer as compared to that in the control group at baseline and during late pregnancy. Although the mean P100 latency saw a significant decline in postpartum visits as compared to that in late pregnancy, the values were higher than in the control group. P100 latency at baseline correlated significantly to serum advanced glycated end products' (AGE'S) levels in the GDM group.

CONCLUSION

Our study findings reflect that the diagnosis of GDM is associated with significant changes in VEP during and after pregnancy as compared to that of healthy pregnant women.

Retinal small vessel narrowing in women with gestational diabetes, pregnancy-associated hypertension, or small-for-gestational age babies

Background

Gestational diabetes, pregnancy-associated hypertension and small-for-gestational age babies are all associated with impaired placental vascularisation. This study compared the effects of these conditions the systemic small vessel calibre that was examined in the retina.

Methods

This was a cross-sectional observational study of consecutive pregnant women recruited from an antenatal clinic. Participants underwent a Glucose Tolerance Test, BP measurements, and were examined for small-for-gestational age babies as per national guidelines. They also underwent retinal photography with a non-mydriatic camera, and vessel calibres were measured with a validated semi-quantitative system at a retinal grading centre. Some participants also underwent testing of retinal vascular responsiveness to a flickering light.

Results

Women with gestational diabetes (n = 68) had a higher mean arterial pressure (85 ± 9 mm Hg) than normal pregnant women (n = 27, 80 ± 8 mmHg, p = 0.01). They also had smaller mean retinal arteriole (147.5 ± 13.6 μm and 159.7 ± 6.7 μm respectively, p < 0.01) and venular calibre (221.0 ± 13.4 μm and 232.8 ± 20.1 μm respectively, p < 0.01) than normal. However their babies' mean birth weights were not different from normal (3,311 ± 558 g and 3,401 ± 600 g respectively, p = 0.48). They also demonstrated a trend to reduced retinal arteriolar dilatation (3.5 ± 1.3%, n = 23) in response to vasodilatory stimuli (4.4 ± 1.8%) (n = 11) (p = 0.08) consistent with endothelial dysfunction. Women with pregnancy-associated hypertension (n = 35) had a higher mean arterial pressure (101 ± 12 mm Hg, p < 0.01), a smaller mean retinal arteriolar calibre (139.9 ± 10.6 μm, p < 0.0001), and a lower baby mean birth weight than for normal pregnancies (3,095 ± 443 g, p = 0.02). Likewise, women with small-for-gestational age babies (n = 31) had a higher mean arterial pressure (89 ± 19 mm Hg, p = 0.03), a smaller mean retinal arteriolar calibre (141.6 ± 12.8 μm, p < 0.01) and a lower baby mean birth weight than for normal pregnancies (2,468 ± 324 g, p < 0.0001).

Conclusion

Mean retinal arterial calibre was reduced in women with gestational diabetes, pregnancy-associated hypertension or small-for-gestational age babies. The reduction in calibre was greatest in pregnancy-associated hypertension and small-for-gestational age babies. Systemic arteriole narrowing may contribute to the pathogenesis of placental vascular dysfunction in these conditions.

Review and comparison of retinal vessel calibre and geometry software and their application to diabetes, cardiovascular disease, and dementia

Developments in retinal imaging technologies have enabled the quantitative evaluation of the retinal vasculature. Changes in retinal calibre and/or geometry have been reported in systemic vascular diseases, including diabetes mellitus (DM), cardiovascular disease (CVD), and more recently in neurodegenerative diseases, such as dementia. Several retinal vessel analysis softwares exist, some being disease-specific, others for a broader context. In the research setting, retinal vasculature analysis using semi-automated software has identified associations between retinal vessel calibre and geometry and the presence of or risk of DM and its chronic complications, and of CVD and dementia, including in the general population. In this article, we review and compare the most widely used semi-automated retinal vessel analysis softwares and their associations with ocular imaging findings in common systemic diseases, including DM and its chronic complications, CVD, and dementia. We also provide original data comparing retinal calibre grading in people with Type 1 DM using two softwares, with good concordance.

Retinal microvasculature and risk of spontaneous abortion in multiethnic Southeast Asian women

OBJECTIVE

To better understand the underlying pathogenesis of spontaneous abortion that affects 10%-20% of recognized pregnancies. We used retinal imaging to study the role of systemic microvasculature and the risk of spontaneous abortion.

DESIGN

A prospective multiethnic preconception cohort study conducted in Singapore.

SETTING

Hospital-based.

PATIENT(S)

A total of 1,032 Southeast Asian women who intended to conceive naturally were screened at study entry, among which 480 women spontaneously conceived within the 12-month observation period. After excluding 24 women who were lost to follow-up, we calculated the spontaneous abortion rate among 456 women. Further, we included 379 women for the final association analysis because 63 women did not undergo preconception retinal imaging examination and 14 had other types of pregnancy loss instead of spontaneous abortion.

INTERVENTION(S)

Trained photographers performed retinal examination using a 45-degree nonmydriatic retinal camera at study entry during the preconception screening. Using a semiautomated, computer-based program, we assessed quantitative retinal microvascular measurements, including caliber, fractal dimension, curvature tortuosity, and branching angle. Clinical research coordinators collected information on sociodemographic status, menstrual characteristics, and lifestyle, and assessed blood pressure and anthropometry at study entry.

MAIN OUTCOME MEASURE(S)

We performed a modified Poisson regression model to estimate the relative risk (RR) and 95% confidence interval (CI) for each retinal microvascular feature and its association with spontaneous abortion after adjusting for major confounders such as maternal prepregnancy, body mass index, and previous pregnancy loss history.

RESULT(S)

We reported a spontaneous abortion rate of 13.4% (61 out of 456). Among all retinal microvascular features, retinal arteriolar caliber, retinal arteriolar, and venular curvature tortuosity were associated with a high risk of incident spontaneous abortion. In the regression model, per SD increase in retinal curvature tortuosity was associated with a 25%-34% increased risk of incident spontaneous abortion (arteriolar: unadjusted RR, 1.29 [95% CI, 1.06-1.56] and adjusted RR, 1.26 [1.04-1.53]; venule: unadjusted RR, 1.30 [1.08-1.55] and adjusted RR, 1.34 [1.09-1.64]).

CONCLUSION(S)

Our prospective cohort observed an increased risk of spontaneous abortion among Asian women with more tortuous retinal vessels assessed during the preconception phase. Our results indicate a role of vascular inflammatory and oxidative stress in the pathogenesis of spontaneous abortion.

CLINICAL TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, NCT03531658.

Retinal microvasculature and time to pregnancy in a multi-ethnic pre-conception cohort in Singapore

STUDY QUESTION

Can abnormalities in retinal microvasculature representing adverse microcirculatory perfusion and inflammation shed light on the pathophysiology of female fecundability?

SUMMARY ANSWER

In our prospective study, abnormalities in retinal vascular geometric morphology (i.e. sparser arteriolar fractal and larger venular bifurcation) during pre-conception phase are temporarily associated with a prolonged time-to-pregnancy (TTP).

WHAT IS KNOWN ALREADY

Suboptimal retinal microcirculatory morphology has been associated with obesity, psychological stress and hypertension, all of which are known risk factors for reduced female fecundability.

STUDY DESIGN, SIZE, DURATION

A total of 652 women of Chinese, Malay or Indian ethnicity 18-45 years of age and planning to conceive spontaneously within the next 12 months were recruited during the pre-conception period into the Singapore PREconception Study of long-Term maternal and child Outcomes (S-PRESTO), from February 2015 to October 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

During recruitment, we collected information on socio-demographic factors, menstrual characteristics and lifestyle behaviors and made anthropometric measurements. We assessed the following retinal microvascular features: caliber, branching angle and fractal dimension. We conducted follow-up telephone surveys to track each participant's pregnancy status at 6, 9 and 12 months after enrolment. We ascertained clinical pregnancies via ultrasonography, with TTP measured by the number of menstrual cycles required to achieve a clinical pregnancy over a 1-year follow-up. Then, we performed discrete-time proportional hazards models to estimate the fecundability odds ratio (FOR) and 95% CI for each retinal microvascular feature in association with TTP, after adjusting for major confounders, including body mass index and fasting glycemic level at study entry.

MAIN RESULTS AND THE ROLE OF THE CHANCE

Among 652 recruited women, 276 (42.3%) successfully conceived within 1 year of follow-up. The mean (and SD) was 1.24 (0.05) Df for retinal arteriolar dimension fraction and 78.45 (9.79) degrees for retinal venular branching angle, respectively. Non-linear relationship testing was performed before multiple adjustment in all associations and a non-monotonic association was detected between retinal venular branching angle and TTP. Compared with women in the highest tertile of retinal arteriolar fractal dimension, women in the second tertile had a prolonged TTP (FOR: 0.68; 95% CI: 0.51-0.92), as did women in the lowest tertile (FOR: 0.73; 95% CI: 0.55-0.98). Compared with women in the middle tertile of retinal venular branching angle, women in the highest tertile had a borderline prolonged TTP (FOR: 0.75; 95% CI: 0.56-1.02). No other retinal vascular features were significantly associated with TTP.

LIMITATIONS, REASONS FOR CAUTION

We were unable to adjust for other potential confounding factors such as female sexual function (e.g. frequency of sexual intercourse), which might introduce a residual bias. Moreover, even though this is a prospective cohort design, our findings can identify the temporal relationship but not necessarily infer a causal relationship between maternal microvasculature and TTP. Lastly, our study involving mainly Chinese, Malay and Indian ethnicities might not be generalizable to other races or ethnicities.

WIDER IMPLICATIONS OF THE FINDINGS

Suboptimal microcirculation may lead to reduced female fecundability. In the future, in addition to conventional ultrasonographic evaluation of ovarian and uterine physiological function, assessing the retinal microvasculature might be useful for assessment of ovarian age, fertility prediction and endometrial evaluation before assisted reproductive techniques for fertility treatments.

STUDY FUNDING/COMPETING INTEREST(S)

This research is supported by the Singapore National Research Foundation (NRF) under its Translational and Clinical Research (TCR) Flagship Programme and administered by the Singapore Ministry of Health's National Medical Research Council (NMRC) (Singapore-NMRC/TCR/004-NUS/2008; NMRC/TCR/012-NUHS/2014) and Singapore National Medical Research Council Transition Award (NMRC TA/0027/2014). The authors have no competing interests to declare.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, NCT03531658.

Evaluation of the relationship between HbA1c level and retina choroidal thickness in patients with gestational diabetes mellitus

PURPOSE

To investigate the effect of hemoglobin A1c level on central macular thickness and central, nasal, and temporal choroidal thickness in patients with gestational diabetes mellitus.

METHODS

This retrospective study included 41 patients who had been diagnosed with gestational diabetes mellitus and undergone a 75-g oral glucose tolerance test between 24 and 28 weeks of gestation. They were divided into two groups based on their hemoglobin A1c level (group 1: hemoglobin A1c <6.0% and group 2: hemoglobin A1c ≥6.0%). All patients underwent a complete ophthalmologic examination. The central macular thickness and central, nasal, and temporal choroidal thickness were measured using optical coherence tomography.

RESULTS

Of the 3,016 pregnant women screened, 7.5% (n=228) were diagnosed with gestational diabetes mellitus during the study period and 41 of these patients were included in the study. Group 1 comprised 48 eyes from 24 patients and Group 2 consisted of 34 eyes of 17 patients. The average body mass index values were 30.8 ± 3.3 and 35.1 ± 9.0, respectively (p=0.002). The insulin use rates were 29.2% and 76.5%, respectively (p=0.000). Mean central macular thickness values were 250.8 ± 14.3 µm and 260.9 ± 18.1 µm, respectively, and the difference was significant (p=0.008).

CONCLUSIONS

Although the body mass index and central macular thickness values were significantly higher in Group 2, there was no difference in the central, nasal, and temporal choroidal thickness between the two groups.

Imaging the eye and its relevance to diabetes care

Diabetes is a major cause of vision loss globally, yet this devastating complication is largely preventable. Early detection and treatment of diabetic retinopathy necessitates screening. Ocular imaging is widely used clinically, both for the screening and management of diabetic retinopathy. Common eye conditions, such as glaucoma, cataracts and retinal vessel thrombosis, and signs of systemic conditions, such as hypertension, are frequently revealed. As well as imaging by a skilled clinician during an eye examination, non-ophthalmic clinicians, such as general practitioners, endocrinologists, nurses and trained health workers, can also can carry out diabetic eye screening. This process usually comprises local imaging with remote grading, mostly human grading. However, grading incorporating artificial intelligence is emerging. In a clinical research context, retinal vasculature analyses using semi-automated software in many populations have identified associations between retinal vessel geometry, such as vessel caliber, and the risk of diabetic retinopathy and other chronic complications of type 1 and type 2 diabetes. Similarly, evaluation of corneal nerves by corneal confocal microscopy is revealing diabetes-related abnormalities, and associations with and predictive power for other chronic diabetes complications. As yet, the value of retinal vessel geometry and corneal confocal microscopy measures at an individual level is uncertain. In this article, targeting non-ocular clinicians and researchers, we review existent and emerging ocular imaging and grading tools, including artificial intelligence, and their associations between ocular imaging findings and diabetes and its chronic complications.

Macular vascular changes in pregnant women with gestational diabetes mellitus by optical coherence tomography angiography

Background

Retinal capillary is vulnerable to diabetes, whether gestational diabetes mellitus (GDM) eyes without clinical retinopathy have capillary abnormalities has not been well studied. To observe the microvasculature changes in eyes of GDM women compared with normoglycemic pregnant women and non-pregnant women by optical coherence tomography-angiography (OCT-A).

Methods

GDM women, age-matched normoglycemic pregnant women and non-pregnant women were included in this study. All subjects were examined by OCT-A, vascular density and macular foveal parameters were measured automatically.

Results

Thirty eight non-pregnant women (NC group), thirty pregnant women without GDM (PC group), and thirty one GDM women (GDM group) were included in this study. There was a significant reduction of vascular density in superficial capillary layer, but an increase in deep capillary layer in PC and GDM groups (P < 0.001). When in terms of the average vascular density, the difference was insignificant among these three groups. Although all the measurements were similar between PC and GDM groups, more capillary “dropout” changes were detected in GDM group. Unexpectedly, the abnormal changes of central macular thickness thinning and foveal avascular zone enlargement seen during pregnancy were improved when compared to PC group.

Conclusions

The changes of vascular density implied the redistribution of capillary network from superficial to deep layer under pregnancy and GDM states. Although the transient hyperglycemia aggravates the changes of capillary “dropout”, GDM group revealed the improvement of central macular thickness thinning and foveal avascular zone enlargement during pregnancy.

Gestational Diabetes Mellitus in Southeast Asia: A Scoping Review

A rapid increase in the prevalence of gestational diabetes mellitus (GDM) has been associated with various factors such as urbanization, lifestyle changes, adverse hyperglycemic intrauterine environment, and the resulting epigenetic changes. Despite this, the burden of GDM has not been well-assessed in Southeast Asia. We comprehensively reviewed published Southeast Asian studies to identify the current research trend in GDM in this region. Joanna Briggs Institute's methodology was used to guide the scoping review. The synthesis of literature findings demonstrates almost comparable clinical evidence in terms of risk factors and complications, challenges presented in diagnosing GDM, and its disease management, given the similarities of the underlying population characteristics in Southeast Asia. Evidence suggests that a large proportion of GDM risk in women may be preventable by lifestyle modifications. However, the GDM burden across countries is expected to rise, given the heterogeneity in screening approaches and diagnostic criteria, mainly influenced by economic status. There is an urgent need for concerted efforts by government and nongovernmental sectors to implement national programs to prevent, manage, and monitor the disease.

Macular and Retinal Nerve Fibre Layer Thickness in Pregnant Women with Gestational Diabetes Mellitus

Background

The information about macular and retinal nerve fibre layer (RNFL) thickness in women with gestational diabetes mellitus (GDM) is scarce. GDM is a risk factor for development of type 2 diabetes mellitus.

Purpose

The purpose of this study was to evaluate mean macular and RNFL thickness in pregnant women with GDM in a teaching institution in Malaysia. We also analyzed the association of age, HbA1c level, duration of GDM, type of treatment, family history, previous history of GDM and spherical equivalent with the macular and RNFL thickness.

Patients and Methods

This was a prospective and cross-sectional study involving 78 pregnant women with GDM, 72 healthy pregnant and 70 healthy non-pregnant women. The study was conducted in Hospital Universiti Sains Malaysia from 2016 to 2018. Macular and RNFL thickness were measured during the third trimester using spectral-domain optical coherence tomography. Age, HbA1c level, duration of GDM, type of treatment, family history, previous history of GDM and spherical equivalent were analysed.

Results

The mean macular thickness was 236.08 (16.44) µm, 237.26 (22.42) µm and 240.66 (20.95) µm for GDM, healthy pregnant, and healthy non-pregnant women. The mean RNFL thickness was 97.27 (9.14) µm, 99.83 (12.44) µm and 97.97 (10.07) µm for GDM, healthy pregnant, and healthy non-pregnant women. There was no significant difference in the mean macular and RNFL thickness in pregnant women with GDM when compared to the control groups (p>0.05). Age, HbA1c, duration of diabetes, treatment received, history of GDM and spherical equivalent did not show significant association with mean macular and retinal thickness (p>0.05).

Conclusion

Pregnant women with GDM have similar thickness of the macular and RNFL with the healthy pregnant and healthy non-pregnant women. Age, HbA1c, duration of diabetes, treatment received, history of GDM and spherical equivalent showed no significant association with mean macular and retinal thickness in pregnant women with GDM.

Relationship between Size of the Foveal Avascular Zone and Carbohydrate Metabolic Disorders during Pregnancy

Aim

To determine whether the area of the foveal avascular zone (FAZ), as a morphological indicator of the microcirculation of the perifoveal capillary network, changes in the carbohydrate metabolism disorders during pregnancy (the gestational age of patients with gestational diabetes mellitus (GDM) and preexisting diabetes (PexD)).

Methods

Ten normal individuals and 41 eyes of 41 patients, 28 with GDM and 13 with PexD, were studied. A 3 × 3 mm area of the FAZ of the superficial capillary plexus layer (SCP) and the deep capillary plexus layer (DCP) was determined by optical coherence tomography angiography (OCTA; RS-3000 Advance, NIDEK). The significance of the correlation between the size of the FAZ and the weeks of pregnancy was determined.

Results

The area of the FAZ of the SCP was 0.38 ± 0.11 mm² (normal eyes), 0.41 ± 0.16 mm² (GDM), and 0.43 ± 0.10 mm² (PexD). The area of the FAZ of the DCP was 0.78 ± 0.23 mm² (normal eyes), 0.69 ± 0.16 mm² (GDM), and 0.79 ± 0.25 mm² (PexD). No significant difference in the FAZ sizes was observed between the groups. The average number of weeks of pregnancy was 24.1 ± 8.2 weeks in the eyes with GDM and 23.3 ± 11.4 weeks in the eyes with PexD (P > 0.05). Significant correlations were found between the size of the FAZ of the SCP and the number of weeks (r = 0.37, P=0.04 for GDM, and r = 0.49, P=0.04 for PexD, Spearman's rank-order correlation coefficient).

Conclusions

For GDM and PexD under established glycemic control, the area of the FAZ is not affected, but vascular changes occurred at the early phase of pregnancy.

Retinal vasculature and 5-year metabolic syndrome among women with gestational diabetes mellitus

BACKGROUND

Women with gestational diabetes mellitus (GDM) are at greater risk of metabolic syndrome (MetS). We studied the association between second-trimester retinal microvasculature and 5-year MetS incidence in women with GDM.

METHODS

A total of 142 mothers with GDM were recruited and followed up 5years after delivery. Retinal photography was performed at 26-28weeks gestation and metabolic outcomes were assessed at the 5-year postpartum follow-up visit. GDM and MetS were defined based on World Health Organization (WHO) guidelines and Adults Treatment Panel (ATP) III guidelines, respectively. Modified-Poisson regression was applied to study the association between second-trimester retinal microvasculature and incident 5-year maternal MetS, after adjusting for major confounders. Area under the curve (AUC) was calculated based on the final model.

RESULTS

Our prospective cohort reported a 9.2% incidence rate of 5-year MetS among women with GDM. After adjusting for maternal age, ethnicity, college degree, pre-pregnancy BMI and fasting glucose at 26-28week gestation, each 10μm widening in retinal venular caliber was associated with an increased relative risk of 1.6 (95% confidence interval [CI]: 1.0, 2.8) in incident MetS. In addition to traditional risks of pre-pregnancy BMI and fasting glucose level at 26-28week gestation, retinal venular caliber mildly increased the prediction of 5-year maternal MetS by 1.8%.

CONCLUSIONS

Second-trimester retinal venular widening was associated with incident 5-year maternal MetS in women with GDM. Our study suggests that mother with GDM at risk of future MetS development may have already presented retinal microvascular abnormalities during pregnancy.

Gestational retinal microvasculature and the risk of 5 year postpartum abnormal glucose metabolism

AIMS/HYPOTHESIS

Changes in retinal microvasculature may reflect insulin resistance. We examined the association of changes in retinal microvasculature during pregnancy and risk of subsequent abnormal glucose metabolism in a cohort of mothers at baseline and 5 years postpartum.

METHODS

Of the participants from the Singapore birth cohort (Growing Up in Singapore Towards Healthy Outcomes [GUSTO]), 276 mothers attended both baseline (at 26-28 weeks of gestation) and follow-up (5 year postpartum) visits. At baseline we performed retinal photography and assessed retinal microvascular variables using a validated grading system. At follow-up, we assessed glucose tolerance using a 75 g OGTT. We defined abnormal glucose metabolism if participants: (1) had onset of gestational diabetes mellitus (GDM) in subsequent pregnancies within a 5 year follow-up period (n = 103) or (2) had prediabetes (impaired fasting glucose, impaired glucose tolerance or HbA_1c 5.7-6.4% [39-46 mmol/mol]) and diabetes diagnosed at the 5 year follow-up visit (n = 84), according to WHO guidelines.

RESULTS

The incidence of GDM in subsequent pregnancy and abnormal glucose metabolism 5 years postpartum was 25.2% and 30.4%, respectively. Each 10 μm widening in retinal venular calibre was associated with a significant risk of postpartum abnormal glucose metabolism (RR 1.2 [95% CI 1.0, 1.5]), independent of maternal age, college education, ethnicity, pre-pregnancy BMI and GDM at baseline. Narrower retinal arteriolar calibre and venular branching angle at baseline was associated with a higher insulin resistance index (1.4 [95% CI 1.1, 1.7] and 1.3 [95% CI 1.1, 1.6], respectively) at follow-up.

CONCLUSIONS/INTERPRETATION

Retinal microvasculature in pregnant women was associated with abnormal glucose metabolism 5 years postpartum. Alteration of microvascular structure during pregnancy may signal subclinical changes that underlie the development of prediabetes and diabetes.