Can we identify adolescents at high risk for nephropathy before the development of microalbuminuria?

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 HbA_1c, 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 HbA_1c (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.

Management of hypertension and renin-angiotensin-aldosterone system blockade in adults with diabetic kidney disease: Association of British Clinical Diabetologists and the Renal Association UK guideline update 2021

People with type 1 and type 2 diabetes are at risk of developing progressive chronic kidney disease (CKD) and end-stage kidney failure. Hypertension is a major, reversible risk factor in people with diabetes for development of albuminuria, impaired kidney function, end-stage kidney disease and cardiovascular disease. Blood pressure control has been shown to be beneficial in people with diabetes in slowing progression of kidney disease and reducing cardiovascular events. However, randomised controlled trial evidence differs in type 1 and type 2 diabetes and different stages of CKD in terms of target blood pressure. Activation of the renin-angiotensin-aldosterone system (RAAS) is an important mechanism for the development and progression of CKD and cardiovascular disease. Randomised trials demonstrate that RAAS blockade is effective in preventing/ slowing progression of CKD and reducing cardiovascular events in people with type 1 and type 2 diabetes, albeit differently according to the stage of CKD. Emerging therapy with sodium glucose cotransporter-2 (SGLT-2) inhibitors, non-steroidal selective mineralocorticoid antagonists and endothelin-A receptor antagonists have been shown in randomised trials to lower blood pressure and further reduce the risk of progression of CKD and cardiovascular disease in people with type 2 diabetes. This guideline reviews the current evidence and makes recommendations about blood pressure control and the use of RAAS-blocking agents in different stages of CKD in people with both type 1 and type 2 diabetes.

Preventing Cardiovascular Complications in Type 1 Diabetes: The Need for a Lifetime Approach

Cardiovascular disease (CVD) remains the main cause of morbidity and mortality in individuals with type 1 diabetes (T1D). Adolescence appears to be a critical time for the development of early subclinical manifestations of CVD, with these changes likely driven by a deterioration in glycemic control during the progression through puberty, combined with the emergence of numerous other traditional cardiometabolic risk factors (e.g., hypertension, dyslipidemia, smoking, alcohol use, obesity, etc.) which emerge at this age. Although hemoglobin A1C has long been the primary focus of screening and treatment strategies, glycemic control remains poor in youth with T1D. Furthermore, screening for cardiovascular risk factors-which are often elevated in youth with T1D-is suboptimal, and use of pharmacological interventions for hypertension and dyslipidemia remains low. As such, there is a clear need not only for better screening strategies for CVD risk factors in youth, but also early interventions to reduce these, if future CVD events have to be prevented. Accumulating evidence has recently suggested that early increases in urinary albumin excretion, even within the normal range, may identify adolescents with T1D who are at an increased risk of complications, and results from pharmacological intervention with statins and ACE inhibitors in these individuals have been encouraging. These data join a growing evidence highlighting the need for a whole-life approach to prevention starting from childhood if efforts to improve CVD outcomes and related mortality in T1D are to be maintained.

Determinants of Cardiovascular Risk in 7000 Youth With Type 1 Diabetes in the Australasian Diabetes Data Network

CONTEXT

Cardiovascular disease occurs prematurely in type 1 diabetes. The additional risk of overweight is not well characterized.

OBJECTIVE

The primary aim was to measure the impact of body mass index (BMI) in youth with type 1 diabetes on cardiovascular risk factors. The secondary aim was to identify other determinants of cardiovascular risk.

DESIGN

Observational longitudinal study of 7061 youth with type 1 diabetes followed for median 7.3 (interquartile range [IQR] 4-11) years over 41 (IQR 29-56) visits until March 2019.

SETTING

15 tertiary care diabetes centers in the Australasian Diabetes Data Network.Participants were aged 2 to 25 years at baseline, with at least 2 measurements of BMI and blood pressure.

MAIN OUTCOME MEASURE

Standardized systolic and diastolic blood pressure scores and non-high-density lipoprotein (HDL) cholesterol were co-primary outcomes. Urinary albumin/creatinine ratio was the secondary outcome.

RESULTS

BMI z-score related independently to standardized blood pressure z- scores and non-HDL cholesterol. An increase in 1 BMI z-score related to an average increase in systolic/diastolic blood pressure of 3.8/1.4 mmHg and an increase in non-HDL cholesterol (coefficient + 0.16 mmol/L, 95% confidence interval [CI], 0.13-0.18; P < 0.001) and in low-density lipoprotein (LDL) cholesterol. Females had higher blood pressure z-scores, higher non-HDL and LDL cholesterol, and higher urinary albumin/creatinine than males. Indigenous youth had markedly higher urinary albumin/creatinine (coefficient + 2.15 mg/mmol, 95% CI, 1.27-3.03; P < 0.001) and higher non-HDL cholesterol than non-Indigenous youth. Continuous subcutaneous insulin infusion was associated independently with lower non-HDL cholesterol and lower urinary albumin/creatinine.

CONCLUSIONS

BMI had a modest independent effect on cardiovascular risk. Females and Indigenous Australians in particular had a more adverse risk profile.

Biomarkers associated with early stages of kidney disease in adolescents with type 1 diabetes

OBJECTIVES

To identify biomarkers of renal disease in adolescents with type 1 diabetes (T1D) and to compare findings in adults with T1D.

METHODS

Twenty-five serum biomarkers were measured, using a Luminex platform, in 553 adolescents (median [interquartile range] age: 13.9 [12.6, 15.2] years), recruited to the Adolescent Type 1 Diabetes Cardio-Renal Intervention Trial. Associations with baseline and final estimated glomerular filtration rate (eGFR), rapid decliner and rapid increaser phenotypes (eGFR slopes <-3 and > 3 mL/min/1.73m² /year, respectively), and albumin-creatinine ratio (ACR) were assessed. Results were also compared with those obtained in 859 adults (age: 55.5 [46.1, 64.4) years) from the Scottish Diabetes Research Network Type 1 Bioresource.

RESULTS

In the adolescent cohort, baseline eGFR was negatively associated with trefoil factor-3, cystatin C, and beta-2 microglobulin (B2M) (B coefficient[95%CI]: -0.19 [-0.27, -0.12], P = 7.0 × 10^-7 ; -0.18 [-0.26, -0.11], P = 5.1 × 10^-6 ; -0.12 [-0.20, -0.05], P = 1.6 × 10^-3 ), in addition to clinical covariates. Final eGFR was negatively associated with osteopontin (-0.21 [-0.28, -0.14], P = 2.3 × 10^-8 ) and cystatin C (-0.16 [-0.22, -0.09], P = 1.6 × 10^-6 ). Rapid decliner phenotype was associated with osteopontin (OR: 1.83 [1.42, 2.41], P = 7.3 × 10^-6 ), whereas rapid increaser phenotype was associated with fibroblast growth factor-23 (FGF-23) (1.59 [1.23, 2.04], P = 2.6 × 10^-4 ). ACR was not associated with any of the biomarkers. In the adult cohort similar associations with eGFR were found; however, several additional biomarkers were associated with eGFR and ACR.

CONCLUSIONS

In this young population with T1D and high rates of hyperfiltration, osteopontin was the most consistent biomarker associated with prospective changes in eGFR. FGF-23 was associated with eGFR increases, whereas trefoil factor-3, cystatin C, and B2M were associated with baseline eGFR.

Vascular Effects of ACE (Angiotensin-Converting Enzyme) Inhibitors and Statins in Adolescents With Type 1 Diabetes

An increased albumin-creatinine ratio within the normal range can identify adolescents at higher risk of developing adverse cardio-renal outcomes as they progress into adulthood. Utilizing a parallel randomized controlled trial and observational cohort study, we characterized the progression of vascular phenotypes throughout this important period and investigated the effect of ACE (angiotensin-converting enzyme) inhibitors and statins in high-risk adolescents. Endothelial function (flow-mediated dilation and reactive hyperemia index) and arterial stiffness (carotid-femoral pulse wave velocity) were assessed in 158 high-risk participants recruited to a randomized, double-blind placebo-controlled 2×2 factorial trial (randomized, placebo-controlled trial) of ACE inhibitors and/or statins in adolescents with type 1 diabetes (AdDIT [Adolescent Type 1 Diabetes cardio-renal Intervention Trial]). Identical measures were also assessed in 215 lower-risk individuals recruited to a parallel observational study. In the randomized, placebo-controlled trial, high-risk patients randomized to ACE inhibitors had improved flow-mediated dilation after 2 to 4 years of follow-up (mean [95% CI]: 6.6% [6.0-7.2] versus 5.3% [4.7-5.9]; P=0.005), whereas no effect was observed following statin use (6.2% [5.5-6.8] versus 5.8% [5.1-6.4]; P=0.358). In the observational study, patients classed as high-risk based on albumin-creatinine ratio showed evidence of endothelial dysfunction at the end of follow-up (flow-mediated dilation=4.8% [3.8-5.9] versus 6.3% [5.8-6.7] for high-risk versus low-risk groups; P=0.015). Neither reactive hyperemia index nor pulse wave velocity were affected by either treatment (P>0.05 for both), but both were found to increase over the duration of follow-up (0.07 [0.03-0.12]; P=0.001 and 0.5 m/s [0.4-0.6]; P<0.001 for reactive hyperemia index and pulse wave velocity, respectively). ACE inhibitors improve endothelial function in high-risk adolescents as they transition through puberty. The longer-term protective effects of this intervention at this early age remain to be determined. Registration- URL: https://www.clinicaltrials.gov; Unique identifier NCT01581476.

Elevated high-density lipoprotein in adolescents with Type 1 diabetes is associated with endothelial dysfunction in the presence of systemic inflammation

AIMS

High-density lipoprotein (HDL) function may be altered in patients with chronic disease, transforming the particle from a beneficial vasoprotective molecule to a noxious pro-inflammatory equivalent. Adolescents with Type 1 diabetes often have elevated HDL, but its vasoprotective properties and relationship to endothelial function have not been assessed.

METHODS AND RESULTS

Seventy adolescents with Type 1 diabetes (age 10-17 years) and 30 age-matched healthy controls supplied urine samples for the measurement of early renal dysfunction (albumin:creatinine ratio; ACR), blood samples for the assessment of cardiovascular risk factors (lipid profiles, HDL functionality, glycaemic control, and inflammatory risk score), and had their conduit artery endothelial function tested using flow-mediated dilation (FMD). HDL-c levels (1.69 ± 0.41 vs. 1.44 ± 0.29mmol/L; P < 0.001), and glycated haemoglobin (HbA1c) (8.4 ± 1.2 vs. 5.4 ± 0.2%; P < 0.001) were increased in all patients compared with controls. However, increased inflammation and HDL dysfunction were evident only in patients who also had evidence of early renal dysfunction (mean ± standard deviation for high-ACR vs. low-ACR and healthy controls: inflammatory risk score 11.3 ± 2.5 vs. 9.5 ± 2.4 and 9.2 ± 2.4, P < 0.01; HDL-mediated nitric-oxide bioavailability 38.0 ± 8.9 vs. 33.3 ± 7.3 and 25.0 ± 7.7%, P < 0.001; HDL-mediated superoxide production 3.71 ± 3.57 vs. 2.11 ± 3.49 and 1.91 ± 2.47nmol O2 per 250 000 cells, P < 0.05). Endothelial function (FMD) was impaired only in those who had both a high inflammatory risk score and high levels of HDL-c (P < 0.05).

CONCLUSION

Increased levels of HDL-c commonly observed in individuals with Type 1 diabetes may be detrimental to endothelial function when accompanied by renal dysfunction and chronic inflammation.

Renal and Cardiovascular Risk According to Tertiles of Urinary Albumin-to-Creatinine Ratio: The Adolescent Type 1 Diabetes Cardio-Renal Intervention Trial (AdDIT)

OBJECTIVE

Baseline data from the Adolescent Type 1 Diabetes Cardio-Renal Intervention Trial (AdDIT) indicated that tertiles of urinary albumin-to-creatinine ratios (ACRs) in the normal range at age 10-16 years are associated with risk markers for diabetic nephropathy (DN) and cardiovascular disease (CVD). We aimed to determine whether the top ACR tertile remained associated with DN and CVD risk over the 2-4-year AdDIT study.

RESEARCH DESIGN AND METHODS

One hundred fifty adolescents (mean age 14.1 years [SD 1.6]) with baseline ACR in the upper tertile (high-ACR group) recruited to the AdDIT trial, who remained untreated, and 396 (age 14.3 years [1.6]) with ACR in the middle and lower tertiles (low-ACR group), who completed the parallel AdDIT observational study, were evaluated prospectively with assessments of ACR and renal and CVD markers, combined with carotid intima-media thickness (cIMT) at baseline and end of study.

RESULTS

After a median follow-up of 3.9 years, the cumulative incidence of microalbuminuria was 16.3% in the high-ACR versus 5.5% in the low-ACR group (log-rank P < 0.001). Cox models showed independent contributions of the high-ACR group (hazard ratio 4.29 [95% CI 2.08-8.85]) and HbA_1c (1.37 [1.10-1.72]) to microalbuminuria risk. cIMT change from baseline was significantly greater in the high- versus low-ACR group (mean difference 0.010 mm [0.079], P = 0.006). Changes in estimated glomerular filtration rate, systolic blood pressure, and hs-CRP were also significantly greater in the high-ACR group (P < 0.05).

CONCLUSIONS

ACR at the higher end of the normal range at the age of 10-16 years is associated with an increased risk of progression to microalbuminuria and future CVD risk, independently of HbA_1c.

Cardiovascular autonomic dysfunction predicts increasing albumin excretion in type 1 diabetes

OBJECTIVE

To determine the potential role of cardiovascular autonomic dysfunction in the development of renal complications in young people with type 1 diabetes (T1D).

METHODS

In this prospective study, 199 children and adolescents recruited to the Oxford Regional Prospective Study underwent assessment of autonomic function ~5 years after diagnosis, and were subsequently followed with longitudinal assessments of HbA_1c and urine albumin-creatinine ratio (ACR) over 8.6 ± 3.4 years. Autonomic function was assessed with 4 standardized tests of cardiovascular reflexes: heart rate (HR) response to (1) Valsalva Maneuver, (2) deep breathing, (3) standing, and (4) blood pressure (BP) response to standing. Linear mixed models were used to assess the association between autonomic parameters and future changes in ACR.

RESULTS

Independent of HbA_1c , each SD increase in HR response to Valsalva Maneuver predicted an ACR increase of 2.16% [95% CI: 0.08; 4.28] per year (P = .04), while each SD increase in diastolic BP response to standing predicted an ACR increase of 2.55% [95% CI: 0.37; 4.77] per year (P = .02). The effect of HR response to standing on ACR reached borderline significance (-2.07% [95% CI: -4.11; 0.01] per year per SD increase, P = .051).

CONCLUSIONS

In this cohort of young people with T1D, enhanced cardiovascular reflexes at baseline predicted future increases in ACR. These results support a potential role for autonomic dysfunction in the pathogenesis of diabetic nephropathy.

The Adolescent Cardio-Renal Intervention Trial (AdDIT): retinal vascular geometry and renal function in adolescents with type 1 diabetes

AIMS/HYPOTHESIS

We examined the hypothesis that elevation in urinary albumin creatinine ratio (ACR) in adolescents with type 1 diabetes is associated with abnormal retinal vascular geometry (RVG) phenotypes.

METHODS

A cross-sectional study at baseline of the relationship between ACR within the normoalbuminuric range and RVG in 963 adolescents aged 14.4 ± 1.6 years with type 1 diabetes (median duration 6.5 years) screened for participation in AdDIT. A validated algorithm was used to categorise log₁₀ ACR into tertiles: upper tertile ACR was defined as 'high-risk' for future albuminuria and the lower two tertiles were deemed 'low-risk'. RVG analysis, using a semi-automated computer program, determined retinal vascular calibres (standard and extended zones) and tortuosity. RVG measures were analysed continuously and categorically (in quintiles: Q1-Q5) for associations with log₁₀ ACR and ACR risk groups.

RESULTS

Greater log₁₀ ACR was associated with narrower vessel calibres and greater tortuosity. The high-risk group was more likely to have extended zone vessel calibres in the lowest quintile (arteriolar Q1 vs Q2-Q5: OR 1.67 [95% CI 1.17, 2.38] and venular OR 1.39 [0.98, 1.99]) and tortuosity in the highest quintile (Q5 vs Q1-Q4: arteriolar OR 2.05 [1.44, 2.92] and venular OR 2.38 [1.67, 3.40]). The effects of retinal vascular calibres and tortuosity were additive such that the participants with the narrowest and most tortuous vessels were more likely to be in the high-risk group (OR 3.32 [1.84, 5.96]). These effects were independent of duration, blood pressure, BMI and blood glucose control.

CONCLUSIONS/INTERPRETATION

Higher ACR in adolescents is associated with narrower and more tortuous retinal vessels. Therefore, RVG phenotypes may serve to identify populations at high risk of diabetes complications during adolescence and well before onset of clinical diabetes complications.

ACE Inhibitors and Statins in Adolescents with Type 1 Diabetes

BACKGROUND

Among adolescents with type 1 diabetes, rapid increases in albumin excretion during puberty precede the development of microalbuminuria and macroalbuminuria, long-term risk factors for renal and cardiovascular disease. We hypothesized that adolescents with high levels of albumin excretion might benefit from angiotensin-converting-enzyme (ACE) inhibitors and statins, drugs that have not been fully evaluated in adolescents.

METHODS

We screened 4407 adolescents with type 1 diabetes between the ages of 10 and 16 years of age and identified 1287 with values in the upper third of the albumin-to-creatinine ratios; 443 were randomly assigned in a placebo-controlled trial of an ACE inhibitor and a statin with the use of a 2-by-2 factorial design minimizing differences in baseline characteristics such as age, sex, and duration of diabetes. The primary outcome for both interventions was the change in albumin excretion, assessed according to the albumin-to-creatinine ratio calculated from three early-morning urine samples obtained every 6 months over 2 to 4 years, and expressed as the area under the curve. Key secondary outcomes included the development of microalbuminuria, progression of retinopathy, changes in the glomerular filtration rate, lipid levels, and measures of cardiovascular risk (carotid intima-media thickness and levels of high-sensitivity C-reactive protein and asymmetric dimethylarginine).

RESULTS

The primary outcome was not affected by ACE inhibitor therapy, statin therapy, or the combination of the two. The use of an ACE inhibitor was associated with a lower incidence of microalbuminuria than the use of placebo; in the context of negative findings for the primary outcome and statistical analysis plan, this lower incidence was not considered significant (hazard ratio, 0.57; 95% confidence interval, 0.35 to 0.94). Statin use resulted in significant reductions in total, low-density lipoprotein, and non-high-density lipoprotein cholesterol levels, in triglyceride levels, and in the ratio of apolipoprotein B to apolipoprotein A1, whereas neither drug had significant effects on carotid intima-media thickness, other cardiovascular markers, the glomerular filtration rate, or progression of retinopathy. Overall adherence to the drug regimen was 75%, and serious adverse events were similar across the groups.

CONCLUSIONS

The use of an ACE inhibitor and a statin did not change the albumin-to-creatinine ratio over time. (Funded by the Juvenile Diabetes Research Foundation and others; AdDIT ClinicalTrials.gov number, NCT01581476 .).

Albuminuria, Proteinuria, and Renal Disease Progression in Children with CKD

BACKGROUND AND OBJECTIVES

The role of albuminuria as an indicator of progression has not been investigated in children with CKD in the absence of diabetes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Children were enrolled from 49 centers of the CKD in Children study between January of 2005 and March of 2014. Cross-sectional multivariable linear regression (n=647) was used to examine the relationship between urine protein-to-creatinine (UP/C [milligrams per milligram]) and albumin-to-creatinine (ACR [milligrams per gram]) with eGFR (milliliters per minute per 1.73 m2). Parametric time-to-event analysis (n=751) was used to assess the association of UP/C, ACR, and urine nonalbumin-to-creatinine (Unon-alb/cr [milligrams per gram]) on the time to the composite endpoint of initiation of RRT or 50% decline in eGFR.

RESULTS

The median follow-up time was 3.4 years and 202 individuals experienced the event. Participants with a UP/C≥0.2 mg/mg and ACR≥30 mg/g had a mean eGFR that was 16 ml/min per 1.73 m2 lower than those with a UP/C<0.2 mg/mg and ACR<30 mg/g. Individuals with ACR<30 mg/g, but a UP/C≥0.2 mg/mg, had a mean eGFR that was 9.3 ml/min per 1.73 m2 lower than those with a UP/C<0.2 mg/mg and ACR<30 mg/g. When categories of ACR and Unon-alb/cr were created on the basis of clinically meaningful cutoff values of UP/C with the same sample sizes for comparison, the relative times (RTs) to the composite end-point were almost identical when comparing the middle (RT=0.31 for UP/C [0.2-2.0 mg/mg], RT=0.38 for ACR [56-1333 mg/g], RT=0.31 for Unon-alb/cr [118-715 mg/g]) and the highest (RT=0.08 for UP/C [>2.0 mg/mg], RT=0.09 for ACR [>1333 mg/g], RT=0.07 for Unon-alb/cr [>715 mg/g]) levels to the lowest levels. A similar trend was seen when categories were created on the basis of clinically meaningful cutoff values of ACR (<30, 30-300, >300 mg/g).

CONCLUSIONS

In children with CKD without diabetes, the utility of an initial UP/C, ACR, and Unon-alb/cr for characterizing progression is similar.

Banting Memorial Lecture 2016 Reducing lifetime risk of complications in adolescents with Type 1 diabetes

Adolescence is a challenging period of life for any young person, and for those with Type 1 diabetes, physiological and psychological factors can result in a deterioration in glycaemic control. In young people with Type 1 diabetes, puberty may be an additional risk factor impacting on the lifetime risk for renal and cardiovascular complications. Our longitudinal studies have identified that increases in urinary albumin excretion through childhood are associated with the development of microalbuminuria and a generalized endotheliopathy linked to cardiovascular risk. Screening of participants recruited to the Adolescent type 1 Diabetes cardio-renal Intervention Trial (AdDIT) confirms that these early changes in albumin excretion are related to both diabetic nephropathy and cardiovascular risk; in part, independent of glycaemic control. Thus, as well as current attempts to improve glycaemic control through enhanced targeted insulin delivery, pumps, sensors and closed loop, we have explored the role of angiotensin-converting enzyme inhibitors and statins in providing cardio-renal protection during adolescence.

The effect of obesity and type 1 diabetes on renal function in children and adolescents

BACKGROUND

Early signs of renal complications can be common in youths with type 1 diabetes (T1D). Recently, there has been an increasing interest in potential renal complications associated with obesity, paralleling the epidemics of this condition, although there are limited data in children.

HYPOTHESIS

Obese children and adolescents present signs of early alterations in renal function similar to non-obese peers with T1D.

SUBJECTS

Eighty-three obese (age: 11.6 ± 3.0 yr), 164 non-obese T1D (age: 12.4 ± 3.2 yr), and 71 non-obese control (age: 12.3 ± 3.2 yr) children and adolescents were enrolled in the study.

METHODS

Anthropometric parameters and blood pressure were measured. Renal function was assessed by albumin excretion rate (AER), serum cystatin C, creatinine and estimated glomerular filtration rate (e-GFR), calculated using the Bouvet's formula.

RESULTS

Obese and non-obese T1D youths had similar AER [8.9(5.9-10.8) vs. 8.7(5.9-13.1) µg/min] and e-GFR levels (114.8 ± 19.6 vs. 113.4 ± 19.1 mL/min), which were higher than in controls [AER: 8.1(5.9-8.7) µg/min, e-GFR: 104.7 ± 18.9 mL/min]. Prevalence of microalbuminuria and hyperfiltration was similar between obese and T1D youths and higher than their control peers (6.0 vs. 8.0 vs. 0%, p = 0.02; 15.9 vs. 15.9 vs. 4.3%, p = 0.03, respectively). Body mass index (BMI) z-score was independently related to e-GFR (r = 0.328; p < 0.001), and AER (r = 0.138; p = 0.017). Hemoglobin A1c (HbA1c) correlated with AER (r = 0.148; p = 0.007) but not with eGFR (r = 0.041; p = 0.310).

CONCLUSIONS

Obese children and adolescents show early alterations in renal function, compared to normal weight peers, and they have similar renal profiles than age-matched peers with T1D.

Early atherosclerosis relates to urinary albumin excretion and cardiovascular risk factors in adolescents with type 1 diabetes: Adolescent type 1 Diabetes cardio-renal Intervention Trial (AdDIT)

OBJECTIVE

The origins of cardiovascular and renal disease in type 1 diabetes begin during childhood. We aimed to evaluate carotid (cIMT) and aortic intima-media thickness (aIMT) and their relationship with cardiovascular risk factors and urinary albumin excretion in adolescents with type 1 diabetes in the Adolescent Type 1 Diabetes cardio-renal Intervention Trial (AdDIT).

RESEARCH DESIGN AND METHODS

A total of 406 adolescents with type 1 diabetes, who were 14.1 ± 1.9 years old with type 1 diabetes duration of 6.7 ± 3.7 years, and 57 age-matched control subjects provided clinical and biochemical data and ultrasound measurements of vascular structure (cIMT and aIMT). Vascular endothelial and smooth muscle function was also measured in 123 of 406 with type 1 diabetes and all control subjects.

RESULTS

In type 1 diabetic subjects, mean/maximal aIMT (P < 0.006; <0.008), but not mean/maximal cIMT, was greater than in control subjects. Mean/maximal aIMT related to urinary albumin-to-creatinine ratio (multiple regression coefficient [SE], 0.013 [0.006], P = 0.03; 0.023 [0.007], P = 0.002), LDL cholesterol (0.019 [0.008], P = 0.02; 0.025 [0.011], P = 0.02), and age (0.010 [0.004], P = 0.004; 0.012 [0.005], P = 0.01), independent of other variables. Mean/maximal cIMT was greater in males (0.023 [0.006], P = 0.02; 0.029 [0.007], P < 0.0001), and mean cIMT related independently to systolic blood pressure (0.001 [0.001], P = 0.04). Vascular smooth muscle function related to aIMT and cIMT but not to urinary albumin excretion.

CONCLUSIONS

aIMT may be a more sensitive marker of atherosclerosis than cIMT in type 1 diabetes during mid-adolescence. Higher urinary albumin excretion, even within the normal range, is associated with early atherosclerosis and should direct clinical attention to modifiable cardiovascular risk factors.

[Importance of diabetic nephropathy in childhood. Clinical findings and basic research in recent decades]

Over the past decades diabetes mellitus is becoming a global pandemic affecting more than 371 million people worldwide. Parallel with the increasing prevalence of type 1 diabetes, there is a growing number of type 2 diabetes cases among children and adolescents that poses new challenges to pediatricians. Diabetic nephropathy is one of the major causes of end stage renal disease, developing in approximately 30% of diabetic patients. However, overt nephropathy is rare in childhood; screening and ongoing assessment for the earliest manifestation of renal injury is extremely important in this young population, as well. Although in the past decades intensive research activity focused on understanding of the pathomechanism of diabetic nephropathy and invention of new therapeutic approaches, prevention and definitive care are still urgently needed. The clinical section of the article summarizes the present state of epidemiology, diagnosis and current therapies of childhood diabetic nephropathy. Then, the authors discuss the state of basic research and show a few promising targets for drug development.

Early elevation of albumin excretion rate is associated with poor gluten-free diet adherence in young people with coeliac disease and diabetes

AIMS

There are conflicting data on microvascular complications in coexisting Type 1 diabetes and coeliac disease. We compared complications rates in youth with or without coeliac disease and examined the association between gluten-free diet adherence and complications.

METHODS

This was a comparative study of adolescents (2510 without coeliac disease, 129 with coeliac disease); 60 (47%) did not adhere to a gluten-free diet--defined as elevated anti-tissue transglutaminase or endomysial immunoglobulin A titres. Retinopathy was detected using 7-field fundal photography and albumin excretion rate by timed overnight urine collections, with early elevation defined as albumin excretion rate ≥ 7.5 μg/min. Logistic regression was used to examine the association between complications and explanatory variables, including coeliac disease vs. no coeliac disease, gluten-free diet adherence vs. non-adherence, diabetes duration and HbA1c .

RESULTS

Median age at last assessment was 16.5 years. Those with coeliac disease vs. those without were younger at diabetes diagnosis (7.1 vs. 8.6 years, P < 0.001) and had longer diabetes duration (9.3 vs. 7.2 years, P < 0.001). HbA1c was lower in those with coeliac disease vs. those without (67 vs. 70 mmol/mol, 8.3 vs. 8.6%, P = 0.04) and adherence to a gluten-free diet vs. non-adherence (66 vs. 72 mmol/mol, 8.2 vs. 8.7%, P = 0.003). There were no differences in complication rates between those with coeliac disease vs. those without (retinopathy 22 vs. 23%, elevated albumin excretion rate 31 vs. 28%). Non-adherence to a gluten-free diet was associated with elevated albumin excretion rate (40 vs. 23%, P = 0.04). In multivariable logistic regression, elevated albumin excretion rate was associated with non-adherence to a gluten-free diet (odds ratio 2.37, 95% CI 1.04-5.40, P = 0.04) and diabetes duration (odds ratio 1.13, 95% CI 1.02-1.25, P = 0.03), but not HbA1c .

CONCLUSIONS

While glycaemic control is better in patients with coeliac disease, non-adherence to a gluten-free diet is associated with elevated albumin excretion rate. The possible protection of a gluten-free diet on complications warrants further investigation.

Adolescent Type 1 Diabetes Cardio-Renal Intervention Trial (AdDIT): urinary screening and baseline biochemical and cardiovascular assessments

OBJECTIVE

We assessed the association between early increases in albumin excretion and cardiovascular (CV) and renal markers in a large cohort of young people with type 1 diabetes.

RESEARCH DESIGN AND METHODS

As part of preliminary screening for a multicenter, randomized controlled trial of statins/ACE inhibitors, we measured albumin-creatinine ratio (ACR) in six early morning urine samples from 3,353 adolescents (10-16 years of age) and calculated tertiles based on an established algorithm. From those subjects deemed to be at higher risk (upper ACR tertile), we recruited 400 into the intervention study (trial cohort). From those subjects deemed to be at lower risk (middle-lower ACR tertiles), we recruited 329 to the observation cohort. At baseline, vascular measurements (carotid intima-media thickness, pulse wave velocity [PWV], flow-mediated dilatation, digital pulse amplitude tonometry), renal markers (symmetric dimethylarginine, cystatin C, creatinine), and CV disease markers (lipids and apolipoproteins [Apo] A-1 and B, C-reactive protein, asymmetric dimethylarginine) were assessed.

RESULTS

Age- and sex-adjusted PWV was higher in the trial than in the observational cohort (5.00 ± 0.84 vs. 4.86 ± 0.70 m/s; P = 0.021). Similarly, non-HDL cholesterol (2.95 ± 0.83 vs. 2.81 ± 0.78 mmol/L; P = 0.02) and ApoB-ApoA-1 ratio (0.50 ± 0.14 vs. 0.47 ± 0.11; P = 0.04) were higher in the trial cohort. Cystatin C and creatinine were decreased (0.88 ± 0.13 vs. 0.90 ± 0.13 mg/L, P = 0.04; 51.81 ± 10.45 vs. 55.35 ± 11.05 μmol/L, P < 0.001; respectively) and estimated glomerular filtration rate (137.05 ± 23.89 vs. 129.31 ± 22.41 mL/min/1.73 m(2); P < 0.001) increased in the trial compared with the observational cohort.

CONCLUSIONS

Our data demonstrate that in adolescents with type 1 diabetes, the group with the highest tertile of albumin excretion showed more evidence of early renal and CV disease than those in the lower tertiles.

Monitoring young people with type 1 diabetes for diabetic nephropathy: potential errors of annual ACR testing

AIM

Type 1 diabetes guidelines recommend annual monitoring of albumin-creatinine ratio (ACR) to detect nephropathy. Annual monitoring for conditions such as dyslipidemia leads to high rates of false-positive diagnoses. We estimated rates of false-positive and false-negative diagnoses under annual, biennial and triennial monitoring.

METHODS

Using Oxford Regional Prospective Study (ORPS) data we modelled ACR over time. Using simulation we estimated numbers of positive and negative diagnoses and the proportion that are false, over 6 years of monitoring, when assessment intervals are 1, 2 or 3 years.

RESULTS

Average increase per year (95%C.I.) in ACR was 3,5% (2,0-5,0%) for males and 4,8% (3,2-6,5%) for females. By 6 years, annual monitoring would lead to 56 (49-63) false-positive diagnoses for every 100 positive diagnoses of micro-albuminuria, biennial to 49 (42-57) false-positives and triennial to 46 (39-53). For every 100 negative diagnoses, annual monitoring would lead to 1,2 (0,8-1,5) false-negatives, biennial to 2,3 (1,7-3,0) and triennial to 3,0 (2,2-3,8).

CONCLUSION

Less frequent monitoring would result in fewer false-positive diagnoses, but increased false negatives, or missed diagnoses. The clinical implications of these scenarios need further investigation through cost-benefit analysis.

Urinary markers of renal inflammation in adolescents with Type 1 diabetes mellitus and normoalbuminuria

AIMS

Patients with the highest albumin:creatinine ratio within the normal range are at an increased risk for developing microalbuminuria. The mechanistic basis for this is unknown, but may be related to renal inflammation. Our goal was to characterize the urinary excretion of cytokines/chemokines in normoalbuminuric adolescents with Type 1 diabetes to determine whether higher range normoalbuminuria is associated with evidence of renal inflammation.

METHODS

Forty-two urinary cytokines/chemokines were measured in subjects who were screened for the Adolescent Type 1 Diabetes Cardio-Renal Intervention Trial. Urinary cytokines/chemokines were compared across low (n = 50), middle (n = 50) or high (n = 50) albumin:creatinine ratio tertile groups.

RESULTS

At baseline, participants in the upper tertile were younger and had shorter diabetes duration compared with the other groups. Other clinical characteristics were similar. Urinary levels of interleukin 6, interleukin 8, platelet-derived growth factor-AA and RANTES differed across albumin:creatinine ratio tertiles, with higher values in patients in the middle and high tertiles compared with the lower tertile (ANCOVA P ≤ 0.01).

CONCLUSIONS

Within the normal albumin:creatinine ratio range, higher urinary albumin excretion is associated with elevated urinary levels of inflammatory markers. Ultimately, this may provide mechanistic insights into disease pathophysiology and stratify the risk of nephropathy in Type 1 diabetes.

When to initiate ACEI/ARB therapy in patients with type 1 and 2 diabetes

Angiotensin converting enzyme inhibitors (ACEI) and angiotensin 2 receptor blockers (ARB) have become a mainstay of adjunctive therapy for the prevention and amelioration of diabetic nephropathy. Although ACEI were shown over 20 years ago to slow the rate of loss of renal function in diabetic subjects with decreased renal function, the question of how early in the course of diabetes to introduce them remains unresolved. Recent studies suggest that very early initiation of ACEI/ARB therapy may not have demonstrable beneficial effects even over a period of years.

Maternal but not paternal association of ambulatory blood pressure with albumin excretion in young offspring with type 1 diabetes

OBJECTIVE

Familial predisposition to hypertension has been associated with the development of diabetic nephropathy in adults, but there are limited data in adolescents. Our aim was to assess whether parental ambulatory blood pressure (ABP) was associated with ABP and albumin excretion in young offspring with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Twenty-four-hour ABP monitoring was performed in 509 young offspring (mean +/- SD age 15.8 +/- 2.3 years) with type 1 diabetes, 311 fathers, and 444 mothers. Systolic (SBP) and diastolic blood pressure (DBP) measurements during 24 h, daytime, and nighttime were calculated. Three early morning urinary albumin-to-creatinine ratios (ACRs), A1C, and anthropometric parameters were available for the offspring.

RESULTS

All paternal ABP parameters, except for nighttime SBP, were independently related to the offspring's ABP (24-h SBP beta = 0.18, 24-h DBP beta = 0.22, daytime SBP beta = 0.25, daytime DBP beta = 0.23, and nighttime DBP beta = 0.18; all P < 0.01). Maternal 24-h DBP (beta = 0.19, P = 0.004), daytime DBP (beta = 0.09, P = 0.04), and nighttime SBP (beta = 0.24 P = 0.001) were related to the corresponding ABP parameter in the offspring. Significant associations were found between the offspring's logACR and maternal ABP. The association with 24-h DBP (beta = 0.16, P = 0.02), daytime DBP (beta = 0.16 P = 0.02), and nighttime DBP (beta = 0.15 P = 0.03) persisted even after adjustment for the offspring's ABP. Mothers of offspring with microalbuminuria had higher ABP than mothers of offspring without microalbuminuria (all P < 0.05).

CONCLUSIONS

In this cohort, parental ABP significantly influenced offspring blood pressure, therefore confirming familial influences on this trait. In addition, maternal ABP, particularly DBP, was closely related to ACR in the offspring, suggesting a dominant effect of maternal genes or an effect of the intrauterine environment on microalbuminuria risk.

Adolescent type 1 Diabetes Cardio-renal Intervention Trial (AdDIT)

Background

The prognosis for young people diagnosed with diabetes during childhood remains poor and this is mainly related to the long-term risk of developing vascular complications.

Microalbuminuria identifies subjects at risk for diabetic nephropathy (DN) and cardiovascular disease (CVD). It is often detected in adolescence but is rarely treated before the age of 18 years, as at the end of puberty albumin excretion may decline and in some subjects will return into the normal range. However, evidence indicates that subjects with both transient and persistent microalbuminuria have experienced renal damage during puberty and thus reno-protection to prevent long-term complications is warranted. In adults with diabetes and microalbuminuria, the use of angiotensin converting enzyme inhibitors (ACEI) and Statins is increasing, and in order to determine whether these agents are of value in the adolescent population a large randomized controlled clinical trial is needed.

Methods/Design

The Adolescent type 1 Diabetes cardio-renal Intervention Trial (AdDIT) is a multi-center, randomized, double-blind, placebo-controlled trial of ACEI and Statin therapy in adolescents with type 1 diabetes. 500 high-risk adolescents, defined on the basis of their albumin excretion, are randomized to receive either ACEI (Quinapril) or Statins (Atorvastatin) or combination therapy or placebo for 3-4 years. There will also be a parallel open observational study, based on the follow-up of 400 low-risk non-randomized adolescents. The major endpoint of the study is the change in albumin excretion; secondary endpoints include markers of CVD, renal function, retinopathy, quality of life combined with assessment of compliance and potential health economic benefits.

Discussion

AdDIT will provide important data on the potential renal and cardiovascular protective effects of ACEI and Statins in high-risk adolescents. Long-term follow-up of the randomized subjects will provide direct evidence of disease outcomes, in addition to the data on early surrogate measures of DN and CVD. Follow-up of non-randomized low-risk subjects will determine the potential impact of intervention on DN and CVD. AdDIT will help to determine whether, in addition to encouraging young people to achieve good glycaemic control, pharmacological cardio-renal protection should also be implemented.

EudraCT Number

2007-001039-72

Trial Registration Number

ISRCTN91419926

Albuminuria in children

PURPOSE OF REVIEW

Albuminuria is a marker of present and future cardiovascular and renal morbidity, and mortality, in adults. Because the roots of these diseases extend back into childhood, assessment of albuminuria has become relevant to child and adolescent clinical care.

RECENT FINDINGS

Normal levels of albumin excretion in children are well below the cut-off for microalbuminuria. In healthy children, albuminuria relates to fasting insulin, but not blood pressure, BMI, lipid levels, fasting glucose, or insulin resistance. In obese children, albuminuria relates to multiple measures of insulin resistance. In children with type 1 diabetes, hemoglobin A1c seems to be the most consistent clinical predictor of microalbuminuria although multiple mechanisms seem to be involved, including genetic polymorphisms. Children with type 2 diabetes and hypertension already exhibit microalbuminuria.

SUMMARY

When considering the population as a whole, children make ideal subjects in which to study the natural history of albuminuria given their relative lack of multiple morbidities commonly seen in adults. The unfortunate rise in 'adult' diseases in the pediatric age group makes this especially relevant. There is a need for longitudinal studies examining predictors of elevated urinary albumin levels as well as potential treatment strategies.

Ambulatory blood pressure measurements are related to albumin excretion and are predictive for risk of microalbuminuria in young people with type 1 diabetes

AIMS/HYPOTHESIS

The relationship between BP and microalbuminuria in young people with type 1 diabetes is not completely clear. As microalbuminuria is preceded by a gradual rise in albumin excretion within the normal range, we hypothesised that ambulatory BP (ABP) may be closely related to albumin excretion and progression to microalbuminuria.

METHODS

ABP monitoring (ABPM) was performed in 509 young people with type 1 diabetes (age median [range]: 15.7 [10.7-22.6] years) followed with annual assessments of three early morning urinary albumin:creatinine ratios (ACRs) and HbA(1c). Systolic BP (SBP) and diastolic BP (DBP) and the nocturnal fall in BP were analysed in relation to ACR.

RESULTS

All ABPM variables were significantly related to baseline log(10) ACR (p < 0.001). After the ABPM evaluation, 287 patients were followed for a median of 2.2 (1.0-5.5) years. ABP at baseline was independently related to mean ACR during follow-up. Nineteen initially normoalbuminuric patients developed microalbuminuria after 2.0 (0.2-4.0) years and their baseline daytime DBP was higher than in normoalbuminuric patients (p < 0.001). After adjusting for baseline ACR and HbA(1c), there was an 11% increased risk of microalbuminuria for each 1 mmHg increase in daytime DBP. Forty-eight per cent of patients were non-dippers for SBP and 60% for DBP; however, ACR was not different between dippers and non-dippers and there were no differences in the nocturnal fall in BP between normoalbuminuric and future microalbuminuric patients.

CONCLUSIONS/INTERPRETATION

In this cohort of young people with type 1 diabetes, ABP was significantly related to ACR, and daytime DBP was independently associated with progression to microalbuminuria. Increasing albumin excretion, even in the normal range, may be associated with parallel rises in BP.

Identifying children at particular risk of long-term diabetes complications

Formerly a 'taboo' subject, long-term complications are now being increasingly discussed with the family by the health-care team. Identifying potential predictors and establishing early intervention can change the course of these complications in the young patient with diabetes. Although the most recognized risk factor is glycaemic exposure, the development of diabetes complications is likely to result from an interaction between genetic and environmental factors. Other major environmental risk factors are hypertension, smoking, higher body mass index and lipid disorders. This article will concentrate on specific paediatric aspects, including the impact of puberty; endothelial dysfunction and genetic susceptibility. Endothelial function assessed by flow-mediated dilatation is a non-invasive method that has been suitable for use in children and adolescents. In type 1 diabetes mellitus children, endothelium dysfunction has been documented among patients with short diabetes duration and has been correlated to folate status, triglyceride and low-density lipoprotein cholesterol levels. Studies in the paediatric population have also revealed an association of diabetes complications with genetic variants in the renin-angiotensin system, polyol pathway, lipid oxidation and folate metabolism. Currently, achieving the best glycaemic control remains the gold standard for prevention of long-term diabetes complications in the clinical context. However, recent identification of genetic markers and development of research tools that predict long-term complications might have a potential role as instruments in assessing the effectiveness of intervention in the early course of the disease.