Relative Hypoxia and Early Diabetic Kidney Disease in Type 1 Diabetes.

The objective of this study was to compare the ratio of renal oxygen availability (RO2) to glomerular filtration rate (GFR), a measure of relative renal hypoxia, in adolescents with and without type 1 diabetes (T1D) and relate the ratio to albuminuria, renal plasma flow (RPF), fat mass, and insulin sensitivity (M/I). RO2 was estimated by blood oxygen level-dependent MRI; fat mass was estimated by DXA; GFR and RPF were estimated by iohexol and p-aminohippurate clearance; albuminuria was estimated by urine albumin-to-creatinine ratio (UACR); and M/I was estimated from steady-state glucose infusion rate/insulin (mg/kg/min) by hyperglycemic clamp in 50 adolescents with T1D (age 16.1 ± 3.0 years, HbA1c 8.6 ± 1.2%) and 20 control patients of similar BMI (age 16.1 ± 2.9 years, HbA1c 5.2 ± 0.2%). The RO2:GFR (ms/mL/min) was calculated as RO2 (T2*, ms) divided by GFR (mL/min). Whole-kidney RO2:GFR was 25% lower in adolescents with T1D versus control patients (P < 0.0001). In adolescents with T1D, lower whole-kidney RO2:GFR was associated with higher UACR (r = -0.31, P = 0.03), RPF (r = -0.52, P = 0.0009), and fat mass (r = -0.33, P = 0.02). Lower medullary RO2:GFR was associated with lower M/I (r = 0.31, P = 0.03). In conclusion, adolescents with T1D exhibited relative renal hypoxia that was associated with albuminuria and with increased RPF, fat mass, and insulin resistance. These data suggest a potential role of renal hypoxia in the development of diabetic kidney disease.

Social Determinants of Health Are Associated with Markers of Renal Injury in Adolescents with Type 1 Diabetes.

OBJECTIVE: To examine the relationship between the social determinants of health and markers of early renal injury in adolescent patients with type 1 diabetes (T1D). STUDY DESIGN: Renal outcomes included estimated glomerular filtration rate (eGFR) and albumin-creatinine excretion ratio (ACR). Differences in urinary and serum inflammatory markers also were assessed in relation to social determinants of health. Regression analysis was used to evaluate the association between the Ontario Marginalization Index (ON-Marg) as a measure of the social determinants of health, patient characteristics, ACR, eGFR, and renal filtration status (hyperfiltration vs normofiltration). RESULTS: Participants with T1D (n = 199) with a mean age of 14.4 ± 1.7 years and diabetes duration of 7.2 ± 3.1 years were studied. Mean eGFR was 122.0 ± 19.4 mL/min/1.73 m2. Increasing marginalization was positively associated with eGFR (P < .0001) but not with ACR (P = .605). Greater marginalization was associated with greater median levels of urinary interleukin (IL)-2, IL-12 (p40), macrophage-derived chemokine, monocyte chemoattractant protein-3, and tumor necrosis factor-ß and serum IL-2. ON-Marg was significantly associated with eGFR after we controlled for age, sex, body mass index z score, ethnicity, serum glucose, and hemoglobin A1c in linear regression. A similar association between hyperfiltration and ON-Marg score was observed in multivariable logistic regression. CONCLUSION: Increasing marginalization is significantly associated with both eGFR and hyperfiltration in adolescents with T1D and is associated with significant changes in urinary inflammatory biomarkers. These findings highlight a potentially important interaction between social and biological determinants of health in adolescents with T1D.

Social Determinants of Health Are Associated with Modifiable Risk Factors for Cardiovascular Disease and Vascular Function in Pediatric Type 1 Diabetes.

OBJECTIVE: To evaluate the relationship between social determinants of health (SDH) and cardiovascular disease (CVD) risk factors as well as a measure of arterial stiffness in adolescents with type 1 diabetes (T1D). STUDY DESIGN: SDH were measured with the validated Ontario Marginalization Index, derived from deidentified postal code data and stratified by quintile (first = least deprived; fifth = most deprived). SDH dimensions included material deprivation; ethnic concentration; and measures of dependency and residential instability. Metabolic control (hemoglobin A1c), cardiovascular risk metrics, and pulse wave velocity, as a measure of arterial stiffness, were related to SDH. Data were evaluated from a cohort of Canadian adolescents within the Adolescent Diabetes Cardiorenal Intervention Trial, a T1D clinical trial RESULTS: A total of 704 participants were evaluated, and significant differences in hemoglobin A1c were evident at the extremes of material deprivation (8.4% vs 9.1% for least vs most deprived, P < .01). CVD risk factors were analyzed in 199 participants, with the most deprived reporting significantly less exercise (P = .004) and increased rates of smoking (P = .008). Increased material deprivation was associated with fewer metrics of "ideal" cardiovascular health attained. Arterial stiffness, as measured by pulse wave velocity, was associated positively with age, body mass index z score, and material deprivation. CONCLUSION: Increased material deprivation was associated with poorer glycemic control. Modifiable, lifestyle-related risk factors for CVD and early arterial wall change are associated with SDH and represent a target for clinical intervention to reduce future CVD burden in adolescents with T1D.

Social determinants of health on glycemic control in pediatric type 1 diabetes.

OBJECTIVE: To evaluate the relationship between the social determinants of health (SDH) and glycemic control in a large pediatric type 1 diabetes (T1D) population. STUDY DESIGN: Deprivation Indices (DI) were used to ascertain population-level measures of socioeconomic status, family structure, and ethnicity in patients with T1D followed at The Hospital for Sick Children August 2010-2011 (n = 854). DI quintile scores were determined for individual patients based on de-identified postal codes, and linked to mean patient A1Cs as a measure of glycemic control. We compared mean A1C between the most and least deprived DI quintiles. Associations were estimated controlling for age and sex, and repeated for insulin pump use. RESULTS: The T1D population evaluated in this study was most concentrated in the least and most deprived quintiles of the Material DI. A1C levels were highest in patients with the greatest degree of deprivation (fifth vs first quintile) on the Material DI (9.2% vs 8.3%, P < .0001), Social DI (9.1% vs 8.3%, P < .0001), and Ethnic Concentration Index (8.9% vs 8.4%, P = .03). These relationships between measures of the SDH and A1C were not evident for patients on insulin pumps. On regression analysis, higher A1C was predicted by older age, female sex, not using pump therapy, and being in the most deprived quintile for Material and Social Deprivation, but not Ethnic Concentration. CONCLUSIONS: Measures of the SDH comprising Material and Social Deprivation were significantly associated with suboptimal glycemic control in our pediatric T1D cohort. Use of insulin pump therapy also predicted A1C and may have a moderating effect on these relationships.

Impaired vascular function in obese adolescents with insulin resistance.

OBJECTIVE: To evaluate endothelial function (EF) in a cohort of obese adolescents with impaired insulin sensitivity. STUDY DESIGN: Cardiovascular risk factors and adipocytokines, along with digital hyperemia, were evaluated by peripheral arterial tonometry (PAT) in adolescents with obesity and insulin resistance (IR) in relation to healthy, nonobese controls. RESULTS: The obese and control subjects were of similar age (13.4+/-1.7 years vs 14.0+/-1.4 years) and sex. The obese subjects had IR (mean homeostasis model of assessment [HOMA] score=5.4; 95% confidence interval=3.3-7.5) and significantly greater body mass index (BMI) (BMI z-score 2.4+/-0.2 kg/m(2) vs 0.0+/-0.8 kg/m(2)) and waist circumference (WC) measures (109.6+/-11.1cm vs 70.5+/-9.4 cm) with elevated low-density lipoprotein cholesterol (LDL-C), triglyceride, and high-sensitivity C-reactive protein levels. The mean PAT ratio was significantly lower in obese adolescents compared with controls (1.51+/-0.4 vs 2.06+/-0.4; P=.002), indicative of impaired EF. Linear regression demonstrated associations between PAT ratio and BMI, WC, age, and LDL-C but not between PAT and leptin, resistin, or adiponectin levels or IR. CONCLUSIONS: Obese adolescents with IR exhibited significantly worse EF as assessed by PAT compared with healthy, nonobese controls, and EF showed a significant association with measures of adiposity and other cardiovascular risk factors.

Impaired endothelial function in adolescents with type 1 diabetes mellitus.

OBJECTIVE: To evaluate the effect of a high-fat meal on endothelial function in adolescents with type 1 diabetes mellitus (T1D). STUDY DESIGN: Twenty-three children with T1D, aged 12 to 18 years, and age- and sex-matched healthy control subjects were assessed for baseline macronutrient intake, and endothelial function was measured both fasting and after a standardized fast-food, high-fat breakfast. RESULTS: Endothelial function, assessed noninvasively by peripheral arterial tonometry, was impaired in the T1D group in the fasting state as compared with control subjects (T1D 1.78 +/- 0.4, control subjects 2.06 +/- 0.4, P = .02), and worsened postprandially in both groups (T1D 1.45 +/- 0.3, control subjects 1.71 +/- 0.3, P = .01). Both groups demonstrated significantly elevated triglyceride levels 3.5 hours after ingestion of the high-fat meal (T1D 114.8 +/- 42.8 and control subjects 126.7 +/- 54.9 mg/dL). Nutrient intake in both groups showed higher than recommended intakes of total fat, saturated fat, and cholesterol. CONCLUSIONS: Patients with T1D exhibited worse endothelial function both before and after a high-fat breakfast than their peers. This suggests that patients with T1D are at greater risk of vascular impairment after a high-fat meal, the cumulative effect of which may contribute to the higher atherosclerotic burden observed in T1D.

Phenotypic effects of null and haploinsufficiency of acid-labile subunit in a family with two novel IGFALS gene mutations.

CONTEXT: IGF-I deficiency may result from impairment of GH secretion or action, or from defects in IGF-I synthesis, transport, or action. Complete deficiency of the acid-labile subunit (ALS), previously described in two male patients, the only known inherited alteration in IGF-I transport, is characterized by severe circulating IGF-I and IGF binding protein (IGFBP)-3 deficiency with only mild growth retardation. OBJECTIVE: Our objective was to study the characterization, at biochemical and molecular levels, of the cause for severe circulating IGF-I and IGFBP-3 deficiency in a male patient with mild growth retardation. PATIENTS: We report an adolescent male with delayed growth and pubertal development (Tanner stage I, -2.00 sd score for height at the age of 15.3 yr), profound circulating IGF-I and IGFBP-3 deficiency, and poor response to GH treatment. RESULTS: The index case, as well as one of his brothers, and his sister were found to be compound heterozygotes for two novel IGFALS gene mutations: C540R, a missense point mutation; and S195_197Rdup, a 9-bp duplication. The parents and youngest brother were found to be carriers for one of these two mutations. The three affected siblings had marked reduction of IGF-I and IGFBP-3 levels, undetectable serum levels of ALS, inability to form ternary complexes, and moderate insulin resistance. All of them attained a normal near-adult height (between -1.0 and -0.5 sd score), which was nonetheless lower than that of their heterozygous brother. The IGF system was only modestly affected in the heterozygous carriers. CONCLUSIONS: This study confirms the critical role of ALS in forming ternary complexes and the maintenance of normal levels of IGF-I and IGFBP-3. Insulin resistance, pubertal delay in male patients, and poor GH responsiveness seem to be frequent findings in ALS deficiency. However, haploinsufficiency of the IGFALS gene has no discernible clinical effects with only modest impact on the IGF system.