Review Reports - Relative Leukocyte Telomere Length Is Shorter in Children and Adolescents with Type 1 Diabetes: Screening of Basic Psychosocial Aspects

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The study investigates Relative Leukocyte Telomere Length (rLTL) in a pediatric cohort (n=35) with Type 1 Diabetes (T1D) compared to healthy controls (n=35). It uniquely incorporates psychosocial dimensions, exploring how perceived stress and social support correlate with biological aging markers (telomeres) in young patients.

While LTL shortening is well-documented in adults with T1D, data on pediatric populations is scarce. This study addresses a significant gap in "early-onset" biological aging.

Integrating clinical markers (HbA1c, cortisol, hsCRP) with psychometric data (PedsQL, SiC, PSS) provides a multi-dimensional view of disease impact.

The use of age-matched controls and the inclusion of siblings (68.6%) helps control for the high heritability of telomere length, which is a common confounding variable in such studies.

The study captures a single point in time. Because telomere dynamics can be volatile in childhood, the "weak positive correlation" between diabetes duration and LTL (which contradicts some adult studies) cannot be fully explained without longitudinal data.

The findings show that T1D females with higher social support have longer telomeres, but the study cannot determine if support protects telomeres or if healthier children (with longer telomeres) perceive better support.

Some suggestions to improve the manuscript:

Elaborate on why longer diabetes duration correlated with longer LTL in this study, whereas other literature suggests the opposite. Is this a survivor bias or an effect of insulin therapy?

Expand the discussion on why social support appears protective for girls but not boys. Is this a biological difference in stress processing or a socio-cultural difference in how support is perceived?

Explicitly state that the small sub-group sizes (males vs. females) mean the gender-specific findings should be treated as hypothesis-generating rather than definitive.

Author Response

Dear Professor,

We would like to deeply thank you in advance for your meaningful comments, insightful recommendations, and the time you spent to elaborately review on our work. We ensure that a major revision has been undertaken, in order to improve the presentation of the findings. You can see the changes in the reorganized version of the discussion section. Please find below a point by point reply to your comments:

Elaborate on why longer diabetes duration correlated with longer LTL in this study, whereas other literature suggests the opposite. Is this a survivor bias or an effect of insulin therapy?

We thoroughly agree with this comment, thus we have critically elaborated and further analyzed accordingly in the text. This change can be found in page 10, paragraph 4^th of the discussion section, lines 302-320. Specifically, some researchers have shown that in adult T1D patients, telomere length was not related to diabetes duration (Jeaclos et al, 1998), and others have shown that it was negatively related (Syreeni et al, 2022, Januszewski et al, 2016). In the only longitudinal pediatric study by Tesovnic et al in 2018, diabetes duration did not actually differ between those children with good and those with bad glycemic control, but only the normalized T1D duration with age differed between the two groups. It is not reported how diabetes duration per se was correlated with LTL in the whole group. Thus, literature remains ambiguous in how T1D duration is connected to LTL. From this perspective, our weak correlation on longer diabetes duration with longer LTL, could be attributed to a survivor bias, as our cohort is characterized by short T1D duration (2.00 ± 2.49), and at this disease stage a partial remission phase can moderate insulin needs. Simultaneously, long-term insulin therapy and any insulin dose adjustments could serve to LTL stabilization, or counterbalance any initial LTL shortening.

Expand the discussion on why social support appears protective for girls but not boys. Is this a biological difference in stress processing or a socio-cultural difference in how support is perceived?

Thank you very much for pointing out this interesting field, we agree with your comment. We have revised the manuscript to emphasize this point. The changes can be found at pages 10-11, paragraphs 5^th to 7^th, lines 324-385). Concerning any gender differences in biomarkers between T1D children and healthy control children, we have added a new table (revised Table 4, page 6) in order to evaluate that rLTL shortening in female T1D children was not due to any other biological variable assessed in this study. Moreover, recent literature addresses the sexual dimorphic patterns found is various biological or psychosocial variables, concerning stress processing. We have now revised the manuscript and elaborated in sexual dimorphism by incorporating literature that supports gender-related differences in HPA-axis functionality, in diverse endocrinopathies, in perceiving social support and in psychological needs (references 47, 54, 55, 58, 59). We support that both the biological and socio-cultural aspects, that you mention, are regarded as the main explanations on why social support could appear protective for girls rather than boys. You will, also, see highlighted sentences across the discussion part, where we pointed out the gender-difference in literature and in our findings.

Explicitly state that the small sub-group sizes (males vs. females) mean the gender-specific findings should be treated as hypothesis-generating rather than definitive.

We thoroughly agree with this comment. This is regarded a pilot study, and we mention accordingly in the limitation section, as well as in the conclusion statement. We have now revised the document to explicitly state that the any findings based on the small sub-group sizes should not be treated as definitive, in multiple times in the document. You can see related points across the text (lines 345-346, 384-385, 404-405, 559, 562-563).

We would like to express our deep thankfulness for your valuable comments and recommendations, as well as the time spent to review our work. If further considerations are raised, we will remain at your disposal to address them, in order to further improve the quality of the document.

On behalf of all co-authors

(Please see the attachment)

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The present result on the shorter TL in T1D children should be ascribed to shorter TL in T1D female children only but not to male T1D children. This result suggests that T1D condition itself is not associated with shorter TL. Therefore, the authors should have concentrated their discussion on the gender difference in T1D children, but their discussion along this line is not adequate. Instead, general, and lengthy, discussion on T1D and TL dominates in Discussion section. Thus, Discussion section should be re-organized by deleting unnecessary parts and by adding necessary parts.

Further, gender differences in biomarkers in control and T1D children should be presented. This would help evaluating the TL shortening in female T1D children was due to the presence of T1D.

The association between social support and TL is interesting but the cross-sectional study design of this work, along with very small sample size, limits its significance. More deliberate discussion may be desirable.

Comment on minor point in this manuscript is about digit of numbers in the manuscript. It’s sometimes too much or uncontrolled: e.g., meaningless expression of mean age or blood pressure to 2 decimal (Tables 1 and 2), inconsistent expression of digit, e.g., “T/S ratio 0.899±0.126 vs 0.82±0.121” in Line 148. Please consider and present number of appropriate significant digit for all variables.

Author Response

Dear Professor,

We would like to express our gratitude for your insightful comments and critical contribution to our study. We deeply appreciate the time you spent for reviewing our manuscript. We ensure that a major revision has been undertaken, in order to improve the presentation of the findings and the manuscript’s quality. We explain below, point by point, the details of the revisions undertaken.

The work presented in this manuscript investigated telomere length of T1D children with a case-control manner. The authors found significant TL variations due to T1D and social support only in female children. This study may be potentially interesting but the point of authors’ discussion of the study result seems to be a bit missing the point. The present result on the shorter TL in T1D children should be ascribed to shorter TL in T1D female children only but not to male T1D children. This result suggests that T1D condition itself is not associated with shorter TL. Therefore, the authors should have concentrated their discussion on the gender difference in T1D children, but their discussion along this line is not adequate. Instead, general, and lengthy, discussion on T1D and TL dominates in Discussion section.

Concerning the comment that we analysed, explained and commented on rLTL based on the whole study sample, and not only the female sub-group, we partly agree with this notice, that rLTL seems to differ strongly as a gender-related feature. Nevertheless, we treated the T1D pediatric sample as a whole, and later elaborated on the gender findings, for a number of reasons; Firstly, the initial rLTL difference which accrued by the T-test, between T1D and Healthy Control, is statistically significant (p=0.020). This, was the main reason. Secondly, males with T1D have, also, apparently smaller rLTL than healthy males, but statistically insignificant. This could be attributed to the small sub-group size concerning the male population in our cohort, especially in T1D (n=14), or because the effect of T1D is less intense in males. Third, based on current literature LTL seems shortened in all patients with T1D (maybe shorter for one sex) and we believe that explanations on multiple factors that cause LTL shortening in T1D, should be presented prior to a gender-specific elaboration. There is a recent body of research showing that T1D and LTL have a bidirectional correlation, and targeting the difference that we found only as a gender-related feature, could possibly restrict the meaning of our results.

Thus, Discussion section should be re-organized by deleting unnecessary parts and by adding necessary parts.

We have thoroughly revised, critically limited and re-organised the paragraphs and context of the discussion section, in attempt to highlight the gender – specific difference in the T1D group. We deleted unnecessary parts and added new parts and related references, to elaborate on the sexual dimorphism pattern. You can find the added or revised sentences highlighted across the text in the attached document.

Further, gender differences in biomarkers in control and T1D children should be presented. This would help evaluating the TL shortening in female T1D children was due to the presence of T1D.

Concerning any gender differences in biomarkers between control and T1D children, thank you very much for this recommendation. They are now presented in Table 4, page 6, and definitely serve to evaluate that rLTL shortening in female T1D children was not due to any other biological variable assessed in this study.

We agree with comment. Since the sub-group analysis (gender) is referred to small study sizes, we approached the discussion section with caution to definitive interpretations, but we revised the manuscript in order to incorporate important literature (new references 47, 54, 55, 58, 59) that supports a gender-related differences in cortisol metabolism, in endocrinopathies, in perceiving social support and in psychological needs. We can thoroughly understand that this is regarded a pilot study, and we mention accordingly in the limitation section, in the conclusion paragraph. The changes can be found at pages 10-11, paragraphs 5^th to 7^th, lines 324-385).

Comment on minor point in this manuscript is about digit of numbers in the manuscript. It’s sometimes too much or uncontrolled: e.g., meaningless expression of mean age or blood pressure to 2 decimals (Tables 1 and 2), inconsistent expression of digit, e.g., “T/S ratio 0.899±0.126 vs 0.82±0.121” in Line 148. Please consider and present number of appropriate significant digit for all variables.

Concerning the digit numbers in the manuscript, we thank you for pointing out these important details. We have revised in all the Tables 1, 2 and 3, reducing to 1 or 2 decimals maximum, except the rLTL measurements, and further addressed any inconsistency on digital expression in the text (eg 0.899±0.126 vs 0.820±0.121 in line 148).

We would like to express again our deep thankfulness for your valuable comments and recommendations to enhance the manuscript. If any considerations are raised, we are willing to revise accordingly in order to further elaborate and improve our work.