Study analysis · Journal of Endocrinology, Metabolism and Diabetes of South Africa · 2025
Diabetic men have smaller testicles—even if they’re not overweight.
Men with type 2 diabetes have lower testosterone and smaller testicles than non-diabetic men, no matter their weight.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study looked at a group of men with diabetes and a group without, and noticed that the ones with diabetes tended to have smaller testicles and lower testosterone. But it didn’t watch them over time or change anything — so we can’t say diabetes caused it, just that the two things happened together.
What’s the bottom line?
This study looked at men with and without type 2 diabetes to see how their testicles and hormone levels compare.
How strong is this study?
The study measured things carefully, like testicle size with a special tool, and had a decent number of people. But we don’t know how they picked the men or if other things like diet or medicine affected the results — so we can’t fully trust that diabetes is the only reason for the differences.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
42 / 100
- Randomizationrandomization unclear
- Blindingblinding unclear
- Control group+15/15
- Sample size (n=537)+18.6/20
- Follow-upno follow-up reported
100 / 100
23 / 100
- P-values+15/15
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 540 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
This design cannot establish causation — the findings describe an association, not a cause. This is a cross-sectional study with no randomization or temporal sequence established; therefore, it cannot determine if T2DM causes reduced testicular volume or if other factors are responsible.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding information were disclosed in the provided text.
The study text contains no disclosure of funding sources, author affiliations, or conflicts of interest. While the study appears methodologically sound, the absence of transparency regarding funding or COI limits full assessment of potential bias.
Key takeaways
- 01
Diabetic men had much lower testosterone and smaller testicles than non-diabetic men, even if they weren't overweight.
- 02
In obese diabetic men, bigger testicles were linked to higher weight and waist size.
- 03
Smaller testicles and lower testosterone in diabetic men may mean reduced reproductive health, but the link between bigger testicles and higher weight in diabetics is unexpected and needs more study.
Surprising findings
- In obese men with type 2 diabetes, larger testicular volume correlated with higher body weight and waist circumference.It contradicts the common belief that obesity always shrinks testicles. In non-diabetic men, excess fat typically lowers testosterone and testicle size—but here, the opposite trend emerged only in diabetics.
Practical takeaways
Men with type 2 diabetes should consider getting their testosterone and testicular health checked, even if they’re not overweight.
This was a cross-sectional study—no follow-up or control for medications, diet, or lifestyle factors.
low confidenceWhy this study matters
Diabetes Lowers Testosterone Regardless of Weight
Men with type 2 diabetes had significantly lower total and free testosterone levels compared to healthy men, even when they weren’t obese. The study found p-values < 0.0001 for both testosterone measures, indicating a strong statistical link independent of body weight.
Most people assume low testosterone is just from being overweight—but this shows diabetes itself may be directly harming hormone production, which affects energy, mood, and sexual health.
Smaller Testicles in Diabetics—Even Lean Ones
Testicular volume was significantly reduced in both non-obese (p = 0.0194) and overweight/obese (p = 0.0492) men with T2DM compared to their healthy counterparts, using Prader orchidometer measurements.
Testicle size is rarely discussed, but it’s a direct indicator of reproductive health. This suggests diabetes may be damaging the testes themselves—not just hormones.
The Weird Twist: Bigger Testicles in Obese Diabetics
Among obese men with T2DM, testicular volume positively correlated with body weight (p = 0.0426) and waist circumference (p = 0.0269)—meaning the heavier they were, the larger their testicles appeared.
This flips the script: usually, more fat means smaller testicles. But in diabetics, the opposite happened—raising questions about fat distribution, fluid retention, or hormonal feedback loops.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
This study looked at men with and without type 2 diabetes to see how their testicles and hormone levels compare.
Research results
Diabetic men had much lower testosterone and smaller testicles than non-diabetic men, even if they weren't overweight. In obese diabetic men, bigger testicles were linked to higher weight and waist size.
What this means - more context
Smaller testicles and lower testosterone in diabetic men may mean reduced reproductive health, but the link between bigger testicles and higher weight in diabetics is unexpected and needs more study.
This study investigates whether type 2 diabetes mellitus (T2DM) and obesity affect testicular volume and testosterone levels in men, comparing T2DM patients with age-matched healthy controls.
Men with T2DM had significantly lower total and free testosterone levels regardless of obesity status, and significantly reduced testicular volume compared to healthy men, both in non-obese and overweight/obese groups. Among obese T2DM men, testicular volume correlated positively with body weight and waist circumference.
Methods Used
Cross-sectional study involving 358 T2DM men and 179 age-matched healthy controls; testicular volume measured using Prader orchidometer; serum levels of testosterone, LH, FSH, and SHBG analyzed.
Main Finding
T2DM was associated with significantly lower total testosterone (p < 0.0001), lower free testosterone (p < 0.0001), and reduced testicular volume compared to healthy controls (p = 0.0194 for non-obese, p = 0.0492 for overweight/obese); in obese T2DM men, testicular volume positively correlated with body weight (p = 0.0426) and waist circumference (p = 0.0269).
Confidence Level
Limited - based on abstract only, full methodology not available
Study Flags
Red Flags
- •Full text not available - methodology details cannot be verified
- •No effect sizes or confidence intervals reported in abstract
- •Cross-sectional design cannot prove causation
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Surprising Findings
In obese men with type 2 diabetes, larger testicular volume correlated with higher body weight and waist circumference.
It contradicts the common belief that obesity always shrinks testicles. In non-diabetic men, excess fat typically lowers testosterone and testicle size—but here, the opposite trend emerged only in diabetics.
Practical Takeaways
Men with type 2 diabetes should consider getting their testosterone and testicular health checked, even if they’re not overweight.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 540 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Human Cross-Sectional
Subject
Moderate probability
on the GRADE evidence scale
This study looked at a group of men with diabetes and a group without, and noticed that the ones with diabetes tended to have smaller testicles and lower testosterone. But it didn’t watch them over time or change anything — so we can’t say diabetes caused it, just that the two things happened together.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Larger sample size for a cross-sectional study (n=537)
- Use of standardized tool (Prader orchidometer) for testicular volume measurement
- Comparison of multiple subgroups (T2DM/non-obese, T2DM/obese, controls)
Weaknesses
- Cross-sectional design prevents determination of temporal sequence
- No information on confounding factors (e.g., medications, physical activity, smoking)
- Full methodology not available - based on abstract only
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
This study looked at men with and without type 2 diabetes to see how their testicles and hormone levels compare.
Research results
Diabetic men had much lower testosterone and smaller testicles than non-diabetic men, even if they weren't overweight. In obese diabetic men, bigger testicles were linked to higher weight and waist size.
What this means - more context
Smaller testicles and lower testosterone in diabetic men may mean reduced reproductive health, but the link between bigger testicles and higher weight in diabetics is unexpected and needs more study.
This study investigates whether type 2 diabetes mellitus (T2DM) and obesity affect testicular volume and testosterone levels in men, comparing T2DM patients with age-matched healthy controls.
Men with T2DM had significantly lower total and free testosterone levels regardless of obesity status, and significantly reduced testicular volume compared to healthy men, both in non-obese and overweight/obese groups. Among obese T2DM men, testicular volume correlated positively with body weight and waist circumference.
Methods Used
Cross-sectional study involving 358 T2DM men and 179 age-matched healthy controls; testicular volume measured using Prader orchidometer; serum levels of testosterone, LH, FSH, and SHBG analyzed.
Main Finding
T2DM was associated with significantly lower total testosterone (p < 0.0001), lower free testosterone (p < 0.0001), and reduced testicular volume compared to healthy controls (p = 0.0194 for non-obese, p = 0.0492 for overweight/obese); in obese T2DM men, testicular volume positively correlated with body weight (p = 0.0426) and waist circumference (p = 0.0269).
Confidence Level
Limited - based on abstract only, full methodology not available
Study Flags
Red Flags
- •Full text not available - methodology details cannot be verified
- •No effect sizes or confidence intervals reported in abstract
- •Cross-sectional design cannot prove causation
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Surprising Findings
In obese men with type 2 diabetes, larger testicular volume correlated with higher body weight and waist circumference.
It contradicts the common belief that obesity always shrinks testicles. In non-diabetic men, excess fat typically lowers testosterone and testicle size—but here, the opposite trend emerged only in diabetics.
Practical Takeaways
Men with type 2 diabetes should consider getting their testosterone and testicular health checked, even if they’re not overweight.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 540 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Human Cross-Sectional
Subject
Moderate probability
on the GRADE evidence scale
This study looked at a group of men with diabetes and a group without, and noticed that the ones with diabetes tended to have smaller testicles and lower testosterone. But it didn’t watch them over time or change anything — so we can’t say diabetes caused it, just that the two things happened together.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Larger sample size for a cross-sectional study (n=537)
- Use of standardized tool (Prader orchidometer) for testicular volume measurement
- Comparison of multiple subgroups (T2DM/non-obese, T2DM/obese, controls)
Weaknesses
- Cross-sectional design prevents determination of temporal sequence
- No information on confounding factors (e.g., medications, physical activity, smoking)
- Full methodology not available - based on abstract only
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The study measured things carefully, like testicle size with a special tool, and had a decent number of people. But we don’t know how they picked the men or if other things like diet or medicine affected the results — so we can’t fully trust that diabetes is the only reason for the differences.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
42 / 100
- Randomizationrandomization unclear
- Blindingblinding unclear
- Control group+15/15
- Sample size (n=537)+18.6/20
- Follow-upno follow-up reported
100 / 100
23 / 100
- P-values+15/15
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 540 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
This design cannot establish causation — the findings describe an association, not a cause. This is a cross-sectional study with no randomization or temporal sequence established; therefore, it cannot determine if T2DM causes reduced testicular volume or if other factors are responsible.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding information were disclosed in the provided text.
The study text contains no disclosure of funding sources, author affiliations, or conflicts of interest. While the study appears methodologically sound, the absence of transparency regarding funding or COI limits full assessment of potential bias.