A Novel TSHR Gene Mutation in a Family with Non-autoimmune Hyperthyroidism.

Background: Familial non-autoimmune hyperthyroidism is a rare disorder characterized by the absence of thyroid autoimmunity, particularly TSH receptor antibody [TRAb]. Objective: The aim of this study was to describe a novel TSHR mutation identified in a family of two siblings and their father. Methods: Two siblings presented for endocrine assessment at ages 7 and 14 years with mild T3 toxicosis, and the father presented at 30 years of age with non-autoimmune thyrotoxicosis. Both siblings were treated with oral antithyroid therapy to achieve reasonable symptom control and thyroid function normalization. The father was treated with oral antithyroid therapy, radioactive iodine, thyroidectomy, and thyroid replacement therapy. Peripheral blood DNA was extracted from both affected siblings and father. Mutation analysis of TSHR was carried out by PCR and Sanger sequencing of both strands of the extracted DNA. Results: Both siblings and their father were heterozygous for the missense TSHR variant c.1855G>C, p.[Asp619His], in exon 10. Conclusions: This novel TSHR variant is associated with T3 toxicosis during childhood. Therefore, early identification and treatment may improve patient outcomes.

Socioeconomic representativeness of Australian, Canadian and British cohorts from the paediatric diabetes AdDIT study: comparisons to regional and national data.

BACKGROUND: Given limited data regarding the involvement of disadvantaged groups in paediatric diabetes clinical trials, this study aimed to evaluate the socioeconomic representativeness of participants recruited into a multinational clinical trial in relation to regional and national type 1 diabetes reference populations. METHODS: Retrospective, cross-sectional evaluation of a subset of adolescent type 1 diabetes cardiorenal intervention trial (AdDIT) participants from Australia (n = 144), Canada (n = 312) and the UK (n = 173). Validated national measures of deprivation were used: the Index of Relative Socioeconomic Disadvantage (IRSD) 2016 (Australia), the Material Resources (MR) dimension of the Canadian Marginalisation index 2016 (Canada) and the Index of Multiple Deprivation (IMD) 2015 (UK). Representativeness was assessed by comparing the AdDIT cohort's distribution of deprivation quintiles with that of the local paediatric type 1 diabetes population (regional), and the broader type 1 diabetes population for which the trial's intervention was targeted (national). RESULTS: Recruited study cohorts from each country had higher proportions of participants with higher SES, and significant underrepresentation of lower SES, in relation to their national references. The socioeconomic make-up in Australia mirrored that of the regional population (p = 0.99). For Canada, the 2nd least deprived (p = 0.001) and the most deprived quintiles (p < 0.001) were over- and under-represented relative to the regional reference, while the UK featured higher regional and national SES bias with over-representation and under-representation from the least-deprived and most-deprived quintiles (p < 0.0001). CONCLUSIONS: Significant national differences in trial participation of low SES participants were observed, highlighting limitations in access to clinical research and the importance of reporting sociodemographic representation in diabetes clinical trials. TRIAL REGISTRATION: NCT01581476. Registered on 20 April 2012.

Coexisiting type 1 diabetes and celiac disease is associated with lower Hba1c when compared to type 1 diabetes alone: data from the Australasian Diabetes Data Network (ADDN) registry.

AIM: To compare HbA1c and clinical outcomes in adolescents and young adults with type 1 diabetes (T1D), with or without celiac disease (CD). METHODS: Longitudinal data were extracted from ADDN, a prospective clinical diabetes registry. Inclusion criteria were T1D (with or without CD), ≥ 1 HbA1c measurement, age 16-25 years and diabetes duration ≥ 1 year at last measurement. Multivariable Generalised Estimated Equation models were used for longitudinal analysis of variables associated with HbA1c. RESULTS: Across all measurements, those with coexisting T1D and CD had lower HbA1c when compared to those with T1D alone (8.5 ± 1.5% (69.4 ± 16.8 mmol/mol) vs. 8.7 ± 1.8% (71.4 ± 19.8 mmol/mol); p < 0.001); lower HbA1c was associated with shorter diabetes duration (B = - 0.06; 95% CI - 0.07 to - 0.05; p < 0.001), male sex (B = - 0.24; - 0.36 to - 0.11; p < 0.001), insulin pump therapy use (B = - 0.46; - 0.58 to - 0.34; p < 0.001), coexistence of T1D and CD (B = - 0.28; - 0.48 to - 0.07; p = 0.01), blood pressure (B = - 0.16; - 0.23 to - 0.09; p < 0.001) and body mass index (B = -- 0.03; - 0.02 to - 0.04; p = 0.01) in the normal range. At last measurement, 11.7% of the total population had a HbA1c < 7.0% (53.0 mmol/mol). CONCLUSIONS: Across all measurements, coexisting T1D and CD is associated with lower HbA1c when compared to T1D alone. However, HbA1c is above target in both groups.

Differences in retinopathy prevalence and associated risk factors across 11 countries in three continents: A cross-sectional study of 156,090 children and adolescents with type 1 diabetes.

OBJECTIVE: To examine the prevalence, time trends, and risk factors of diabetic retinopathy (DR) among youth with type 1 diabetes (T1D) from 11 countries (Australia, Austria, Denmark, England, Germany, Italy, Luxemburg, Netherlands, Slovenia, United States, and Wales). SUBJECTS AND METHODS: Data on individuals aged 10-21 years with T1D for >1 year during the period 2000-2020 were analyzed. We used a cross-sectional design using the most recent year of visit to investigate the time trend. For datasets with longitudinal data, we aggregated the variables per participant and observational year, using data of the most recent year to take the longest observation period into account. DR screening was performed through quality assured national screening programs. Multiple logistic regression models adjusted for the year of the eye examination, age, gender, minority status, and duration of T1D were used to evaluate clinical characteristics and the risk of DR. RESULTS: Data from 156,090 individuals (47.1% female, median age 15.7 years, median duration of diabetes 5.2 years) were included. Overall, the unadjusted prevalence of any DR was 5.8%, varying from 0.0% (0/276) to 16.2% between countries. The probability of DR increased with longer disease duration (aORper-1-year-increase  = 1.04, 95% CI: 1.03-1.04, p < 0.0001), and decreased over time (aORper-1-year-increase  = 0.99, 95% CI: 0.98-1.00, p = 0.0093). Evaluating possible modifiable risk factors in the exploratory analysis, the probability of DR increased with higher HbA1c (aORper-1-mmol/mol-increase-in-HbA1c  = 1.03, 95% CI: 1.03-1.03, p < 0.0001) and was higher among individuals with hypertension (aOR = 1.24, 95% CI: 1.11-1.38, p < 0.0001) and smokers (aOR = 1.30, 95% CI: 1.17-1.44, p < 0.0001). CONCLUSIONS: The prevalence of DR in this large cohort of youth with T1D varied among countries, increased with diabetes duration, decreased over time, and was associated with higher HbA1c, hypertension, and smoking.

Global incidence, prevalence, and mortality of type 1 diabetes in 2021 with projection to 2040: a modelling study.

BACKGROUND: Accurate data on type 1 diabetes prevalence, incidence, associated mortality and life expectancy are crucial to inform public health policy, but these data are scarce. We therefore developed a model based on available data to estimate these values for 201 countries for the year 2021 and estimate the projected prevalent cases in 2040. METHODS: We fitted a discrete-time illness-death model (Markov model) to data on type 1 diabetes incidence and type 1 diabetes-associated mortality to produce type 1 diabetes prevalence, incidence, associated mortality and life expectancy in all countries. Type 1 diabetes incidence and mortality data were available from 97 and 37 countries respectively. Diagnosis rates were estimated using data from an expert survey. Mortality was modelled using random-forest regression of published type 1 diabetes mortality data, and life expectancy was calculated accordingly using life tables. Estimates were validated against observed prevalence data for 15 countries. We also estimated missing prevalence (the number of additional people who would be alive with type 1 diabetes if their mortality matched general population rates). FINDINGS: In 2021, there were about 8·4 (95% uncertainty interval 8·1-8·8) million individuals worldwide with type 1 diabetes: of these 1·5 million (18%) were younger than 20 years, 5·4 million (64%) were aged 20-59 years, and 1·6 million (19%) were aged 60 years or older. In that year there were 0·5 million new cases diagnosed (median age of onset 39 years), about 35 000 non-diagnosed individuals died within 12 months of symptomatic onset. One fifth (1·8 million) of individuals with type 1 diabetes were in low-income and lower-middle-income countries. Remaining life expectancy of a 10-year-old diagnosed with type 1 diabetes in 2021 ranged from a mean of 13 years in low-income countries to 65 years in high-income countries. Missing prevalent cases in 2021 were estimated at 3·7 million. In 2040, we predict an increase in prevalent cases to 13·5-17·4 million (60-107% higher than in 2021) with the largest relative increase versus 2021 in low-income and lower-middle-income countries. INTERPRETATION: The burden of type 1 diabetes in 2021 is vast and is expected to increase rapidly, especially in resource-limited countries. Most incident and prevalent cases are adults. The substantial missing prevalence highlights the premature mortality of type 1 diabetes and an opportunity to save and extend lives of people with type 1 diabetes. Our new model, which will be made publicly available as the Type 1 Diabetes Index model, will be an important tool to support health delivery, advocacy, and funding decisions for type 1 diabetes. FUNDING: JDRF International.

Optimal Frequency of Retinopathy Screening in Adolescents With Type 1 Diabetes: Markov Modeling Approach Based on 30 Years of Data.

OBJECTIVE: Current guidelines recommend biennial diabetic retinopathy (DR) screening commencing at the age of 11 years and after 2-5 years' duration of type 1 diabetes. Growing evidence suggests less frequent screening may be feasible. RESEARCH DESIGN AND METHODS: Prospective data were collected from 2,063 youth with type 1 diabetes who were screened two or more times between 1990 and 2019. Baseline (mean ± SD) age was 13.3 ± 1.8 years, HbA1c was 8.6 ± 1.3% (70.1 ± 14.7 mmol/mol), diabetes duration was 5.6 ± 2.8 years, and follow-up time was 4.8 ± 2.8 years. DR was manually graded from 7-field retinal photographs using the Early Treatment Diabetic Retinopathy Study (ETDRS) scale. Markov chain was used to calculate probabilities of DR change over time and hazard ratio (HR) of DR stage transition. RESULTS: The incidence of moderate nonproliferative DR (MNPDR) or worse was 8.6 per 1,000 patient-years. Probabilities of transition to this state after a 3-year interval were from no DR, 1.3%; from minimal DR, 5.1%; and from mild DR, 22.2%, respectively. HRs (95% CIs) for transition per 1% current HbA1c increase were 1.23 (1.16-1.31) from no DR to minimal NPDR, 1.12 (1.03-1.23) from minimal to mild NPDR, and 1.28 (1.13-1.46) from mild to MNPDR or worse. HbA1c alone explained 27% of the transitions between no retinopathy and MNPDR or worse. The addition of diabetes duration into the model increased this value to 31% (P = 0.03). Risk was also increased by female sex and higher attained age. CONCLUSIONS: These results support less frequent DR screening in youth with type 1 diabetes without DR and short duration. Although DR progression to advanced stages is generally slow, higher HbA1c greatly accelerates it.

Epidemiology of Type 1 Diabetes.

PURPOSE OF REVIEW: Epidemiological research on type 1 diabetes (T1D) has traditionally focussed on the paediatric age group, but recent data in adults has confirmed it to be a disease of all ages with a wide clinical spectrum. We review the epidemiology and clinical features of T1D across the lifespan. RECENT FINDINGS: While the peak incidence of T1D is still in early adolescence, T1D is now diagnosed more commonly in adulthood than childhood due to increasing recognition of adult-onset T1D and the length of the adult lifespan. It still follows the known geographic variations in incidence, being highest in Northern Europe and lowest in Asia. The onset of T1D in adulthood is usually less acute than in childhood and confers a lower, although still substantial, risk of complications and early mortality. Interventions to delay T1D onset are emerging and screening for those at risk at birth is increasingly available. Type 1 diabetes can develop at any age and may not present with ketosis or an immediate insulin requirement in adults. Macro- and microvascular complications are the greatest cause of excess morbidity and mortality in this population.

Twenty years of the International Society for Pediatric and Adolescent Diabetes Science Schools programs: Assessment of their impact on the participants' personal careers and networking development.

OBJECTIVE: The following report describes the evaluation of the ISPAD Science School for Physicians (ISSP) and for Healthcare Professionals (ISSHP) in terms of their efficiency and success. METHODS: All past attendees from 2000-2019 ISSP and 2004-2019 ISSHP programs were invited to respond to an online survey to assess perceived outcomes of the programs on career development, scientific enhancement, scientific networking, and social opportunities. RESULTS: One-third of the past ISSP (129/428), and approximately 43% of the past ISSHP attendees (105/245) responded to the surveys. Most of ISSP attendees reported that the programs supported their career (82%) by helping to achieve a research position (59%), being engaged with diabetes care (68%) or research (63%) or starting a research fellowship (59%). Responders indicated that ISSP was effective in increasing interest in diabetes research (87%) and enhancing the number (66%) and quality (83%) of scientific productions, and promotion of international collaborations (86%). After the ISSP, 34% of responders received research grants. From the first round of the ISSHP survey (2004-2013), responders reported have improved knowledge (60%), gained more confidence in research (69%), undertaken a research project (63%), and achieved a higher academic degree (27%). From the second round (2014-2019), participants indicated that the program was valuable/useful in workplace (94%) through understanding (89%) and conducting (68%) research and establishing communication from other participants (64%) or from faculty (42%). After the ISSHP, 17% had received awards. CONCLUSIONS: From the participants' viewpoint, both programs were effective in improving engagement with diabetes research, supporting career opportunities, increasing scientific skills, and enhancing networking and research activities.

Higher frequency of cardiovascular autonomic neuropathy in youth with type 2 compared to type 1 diabetes: Role of cardiometabolic risk factors.

OBJECTIVE: Cardiovascular autonomic neuropathy (CAN) is an overlooked but common and serious diabetes complication. We examined CAN in youth with diabetes and associations with cardiovascular risk factors. RESEARCH DESIGN AND METHODS: This was a prospective cohort of youth aged <20 years with type 2 or type 1 diabetes (n = 66/1153, median age 15.4/16.5 years, duration 1.7/8.0 years), assessed between 2009 and 2020. CAN was defined as ≥2 abnormal heart rate variability measures across time, geometric, and frequency domains. Obesity was defined as BMI ≥ 95th percentile and severe obesity as ≥120% of 95th percentile. Multivariable generalized estimating equations (GEE) were used to examine putative risk factors for CAN, including diabetes type, obesity, and HbA1c . RESULTS: At most recent assessment, youth with type 2 versus type 1 diabetes had median: HbA1 c 7.1% (54 mmol/mol) versus 8.7% (72 mmol/mol) and BMI SDS (2.0 vs. 0.7); frequency of CAN (47% vs. 27%), peripheral nerve abnormality (47% vs. 25%), hypertension (29% vs. 12%), albuminuria (21% vs. 3%), and severe obesity (35% vs. 2%). In multivariable GEE, CAN was associated with type 2 diabetes: Odds Ratio 2.53, 95% CI 1.46, 4.38, p = 0.001, higher BMI SDS: 1.49, 95% CI 1.29, 1.73, p < 0.0001, and obesity: 2.09, 95% CI 1.57, 2.78, p < 0.0001. CONCLUSIONS: Youth with type 2 diabetes have a higher frequency of CAN, peripheral nerve abnormality, hypertension, albuminuria and severe obesity despite shorter diabetes duration and younger age. Our findings highlight the importance of targeting modifiable risk factors to prevent cardiovascular disease in youth with diabetes.

Thirty-Year Time Trends in Diabetic Retinopathy and Macular Edema in Youth With Type 1 Diabetes.

OBJECTIVE: To examine trends in diabetic retinopathy (DR) and diabetic macular edema (DME) in adolescents with type 1 diabetes between 1990 and 2019. RESEARCH DESIGN AND METHODS: We analyzed 5,487 complication assessments for 2,404 adolescents (52.7% female, aged 12-20 years, diabetes duration >5 years), stratified by three decades (1990-1999, 2000-2009, 2010-2019). DR and DME were graded according to the modified Airlie House classification from seven-field stereoscopic fundal photography. RESULTS: Over three decades, the prevalence of DR was 40, 21, and 20% (P < 0.001) and DME 1.4, 0.5, and 0.9% (P = 0.13), respectively, for 1990-1999, 2000-2009, and 2010-2019. Continuous subcutaneous insulin infusion (CSII) use increased (0, 12, and 55%; P < 0.001); mean HbA1c was bimodal (8.7, 8.5, and 8.7%; P < 0.001), and the proportion of adolescents meeting target HbA1c <7% did not change significantly (8.3, 7.7, and 7.1%; P = 0.63). In multivariable generalized estimating equation analysis, DR was associated with 1-2 daily injections (odds ratio 1.88, 95% CI 1.42-2.48) and multiple injections in comparison with CSII (1.38, 1.09-1.74); older age (1.11, 1.07-1.15), higher HbA1c (1.19, 1.05-1.15), longer diabetes duration (1.15, 1.12-1.18), overweight/obesity (1.27, 1.08-1.49) and higher diastolic blood pressure SDS (1.11, 1.01-1.21). DME was associated with 1-2 daily injections (3.26, 1.72-6.19), longer diabetes duration (1.26, 1.12-1.41), higher diastolic blood pressure SDS (1.66, 1.22-2.27), higher HbA1c (1.28, 1.03-1.59), and elevated cholesterol (3.78, 1.84-7.76). CONCLUSIONS: One in five adolescents with type 1 diabetes had DR in the last decade. These findings support contemporary guidelines for lower glycemic targets, increasing CSII use, and targeting modifiable risk factors including blood pressure, cholesterol, and overweight/obesity.

Childhood type 1 diabetes is associated with abnormal bone development.

OBJECTIVE: To describe bone mineral density (BMD), bone structure, and fracture prevalence in adolescents with type 1 diabetes (T1D) and explore their associations with glycemic control and microvascular complications. RESEARCH DESIGN AND METHODS: Cross sectional study of 64 adolescents (38 males) with T1D duration >10 years who underwent dual-energy X-ray absorptiometry (DXA), peripheral quantitative computed tomography (pQCT), fracture survey, plantar fascia thickness, and microvascular complications assessment. RESULTS: Mean age was 16.6 ± 2.1 years, diabetes duration 12.8 ± 2.2 years and HbA1c 8.9 ± 1.7% (74 mmol/mol). Fracture prevalence was 50%. DXA areal BMD (Z-score) was reduced for femoral neck (-0.5 ± 1.3, p = 0.008) and arm (-0.4 ± 1.0, p < 0.001), while total areal BMD and lumbar spine BMD were normal. In pQCT (Z-score), trabecular volumetric BMD (vBMD) was reduced for tibia (-0.4 ± 0.8, p < 0.001) and radius (-0.8 ± 1.4, p < 0.001) whereas cortical vBMD was increased at both sites (tibia: 0.5 ± 0.6, p < 0.001, radius: 0.7 ± 1.5, p < 0.001). Muscle cross-sectional area (CSA) was reduced for upper (-0.6 ± 1.2, p < 0.001) and lower (-0.4 ± 0.7, p < 0.001) limbs. DXA total areal BMD was positively correlated with BMI (p < 0.01) and age at T1D diagnosis (p = 0.04). Lower radial bone CSA, total and lumbar spine BMD were associated with autonomic nerve dysfunction. HbA1c, diabetes duration, fracture history and other microvascular complications were not significantly associated with bone parameters. CONCLUSIONS: Adolescents with childhood-onset T1D have site-specific bone deficits in upper and lower limbs but normal total and lumbar spine BMD. T1D appears to have differential effects on trabecular and cortical bone compartments. Future longitudinal analysis is warranted to examine whether these changes translate in to increased fracture risk.

Management of type 2 diabetes in young adults aged 18-30 years: ADS/ADEA/APEG consensus statement.

INTRODUCTION: Type 2 diabetes in young adults (nominally, 18-30 years of age) is a more aggressive condition than that seen in older age, with a greater risk of major morbidity and early mortality. This first Australian consensus statement on the management of type 2 diabetes in young adults considers areas where existing type 2 diabetes guidance, directed mainly towards older adults, may not be appropriate or relevant for the young adult population. Where applicable, recommendations are harmonised with current national guidance for type 2 diabetes in children and adolescents (aged < 18 years). The full statement is available at https://www.diabetessociety.com.au, https://www.adea.com.au and https://www.apeg.org.au. MAIN RECOMMENDATIONS: Advice is provided on important aspects of care including screening, diabetes type, psychological care, lifestyle, glycaemic targets, pharmacological agents, cardiovascular disease risk management, comorbidity assessment, contraception and pregnancy planning, and patient-centred education. Special considerations for Aboriginal and Torres Strait Islander Australians are highlighted separately. CHANGES IN MANAGEMENT AS A RESULT OF THIS STATEMENT: Management recommendations for young adults, which differ from those for adults, include: ▪screening for diabetes in young adults with overweight or obesity and additional risk factors, including in utero exposure to type 2 diabetes or gestational diabetes mellitus; ▪more stringent glucose targets (glycated haemoglobin ≤ 6.5% [≤ 48 mmol/mol]); ▪in the context of obesity or higher cardio-renal risk, glucagon-like peptide 1 receptor agonists and sodium-glucose cotransporter 2 inhibitors are preferred second line agents; ▪ß-cell decline is more rapid, so frequent review, early treatment intensification and avoidance of therapeutic inertia are indicated; ▪a blood pressure target of < 130/80 mmHg, as the adult target of ≤ 140/90 mmHg is too high; ▪absolute cardiovascular disease risk calculators are not likely to be accurate in this age group; early statin use should therefore be considered; and ▪a multidisciplinary model of care including an endocrinologist and a certified diabetes educator.

Urinary albumin/creatinine ratio tertiles predict risk of diabetic retinopathy progression: a natural history study from the Adolescent Cardio-Renal Intervention Trial (AdDIT) observational cohort.

AIMS/HYPOTHESIS: We hypothesised that adolescents with type 1 diabetes with a urinary albumin/creatinine ratio (ACR) in the upper tertile of the normal range (high ACR) are at greater risk of three-step diabetic retinopathy progression (3DR) independent of glycaemic control. METHODS: This was a prospective observational study in 710 normoalbuminuric adolescents with type 1 diabetes from the non-intervention cohorts of the Adolescent Cardio-Renal Intervention Trial (AdDIT). Participants were classified as 'high ACR' or 'low ACR' (lowest and middle ACR tertiles) using baseline standardised log10 ACR. The primary outcome, 3DR, was determined from centrally graded, standardised two-field retinal photographs. 3DR risk was determined using multivariable Cox regression for the effect of high ACR, with HbA1c, BP, LDL-cholesterol and BMI as covariates; diabetes duration was the time-dependent variable. RESULTS: At baseline mean ± SD age was 14.3 ± 1.6 years and mean ± SD diabetes duration was 7.2 ± 3.3 years. After a median of 3.2 years, 83/710 (12%) had developed 3DR. In multivariable analysis, high ACR (HR 2.1 [1.3, 3.3], p=0.001), higher mean IFCC HbA1c (HR 1.03 [1.01, 1.04], p=0.001) and higher baseline diastolic BP SD score (HR 1.43 [1.08, 1.89], p=0.01) were independently associated with 3DR risk. CONCLUSIONS/INTERPRETATION: High ACR is associated with greater risk of 3DR in adolescents, providing a target for future intervention studies. TRIAL REGISTRATION: isrctn.org ISRCTN91419926.

Sight-threatening retinopathy in nine adolescents with early onset type 1 diabetes.

In adults, there has been a decline in the incidence of diabetic retinopathy (DR) associated with improvements in diabetes management. Data on incident severe DR in adolescents are sparse. In our established diabetes complications assessment service, we recorded nine cases of sight-threatening retinopathy in youth aged 15-17.9 years from 2017 to 2021. Proliferative retinopathy and clinically significant macular oedema were identified. The subjects were diagnosed with type 1 diabetes before the age of 10 years and had a history of poor glycaemic control (HbA1c 86-130 mmol/mol, 10%-15%). Five cases of retinopathy developed rapidly within 2.5 years of a previously normal retinal examination on seven-field stereoscopic retinal photography. Three adolescents required laser photocoagulation therapy. Two adolescents were diagnosed with retinopathy following improvement in diabetes control after being lost to medical follow-up and their retinopathy improved with improved glycaemic control. Thus, we support repeated retinal screening in adolescents with diabetes duration >10 years with suboptimal glycaemic control, even when initial retinal examination is normal, as retinopathy can progress rapidly during adolescence.

Baseline extended zone retinal vascular calibres associate with sensory nerve abnormalities in adolescents with type 1 diabetes: A prospective longitudinal study.

OBJECTIVE: The relationship between retinal vascular calibres (RVCs) and diabetic neuropathy is unclear. We investigated associations between RVCs and sensory nerve abnormality in adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS: In a prospective longitudinal study of 889 adolescents with type 1 diabetes with baseline mean (±SD) age 14.1 ± 1.5 years and HbA1c IFCC 69.4 ± 14.1 mmol/mol (8.6 ± 1.3%), RVCs were assessed from baseline retinal photographs: 'central zone' calibres, summarized as central retinal arteriolar (CRAE) and venular equivalents (CRVE) and 'extended zone' calibres: mean width of arterioles (MWa) and venules (MWv). Sensory nerve abnormality was defined as at least one abnormal sensory quantitative testing from two thermal and two vibration threshold tests measured at foot every 1-2 years. Associations between baseline RVC and sensory nerve function were examined using generalized estimating equations and cumulative risk by Cox regression analyses. RESULTS: During a median study follow-up of 6.2 [IQR 3.7-10.4] years, sensory nerve abnormality was found in 27% of adolescents. Narrower extended zone calibre quartiles but not CRAE or CRVE quartiles were independently associated with sensory nerve abnormality: MWa (Q1 vs. Q2-4: OR 1.35 (95% CI 1.02, 1.61) and MWv (Q1 vs. Q2-4: 1.31 (1.03, 1.7)), after adjusting for HbA1c , duration and blood pressure. Similarly, in Cox regression, the narrowest quartiles were associated with sensory nerve abnormality: MWa hazard ratio (HR) 1.5 (1.3, 1.8) and MWv 1.6 (1.4, 1.9). CONCLUSIONS: Narrower extended zone retinal calibres were associated with sensory nerve abnormality in adolescents with type 1 diabetes and may present useful biomarkers to understand the pathophysiology of neuropathy.