Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.

Persistently high glucose levels in young children with type 1 diabetes

OBJECTIVES

The aim of the study was to characterize glucose levels and variability in young children with type 1 diabetes (T1D).

METHODS

A total of 144 children of 4-10 yr old diagnosed with T1D prior to age 8 were recruited at five DirecNet centers. Participants used a continuous glucose monitor (CGM) every 3 months during an 18-month study. Among the 144 participants, 135 (mean age 7.0 yr, 47% female) had a minimum of 48 h of CGM data at more than five of seven visits and were included in analyses. CGM metrics for different times of day were analyzed.

RESULTS

Mean hemoglobin A1c (HbA1c) at the beginning and end of the study was 7.9% (63 mmol/mol). Fifty percent of participants had glucose levels >180 mg/dL (10.0 mmol/L) for >12 h/d and >250 mg/dL (13.9 mmol/L) for >6 h/d. Median time <70 mg/dL (3.9 mmol/L) was 66 min/d and <60 mg/dL (3.3 mmol/L) was 39 min/d. Mean amplitude of glycemic excursions (MAGE) was lowest overnight (00:00-06:00 hours). The percent of CGM values 71-180 mg/dL (3.9-10.0 mmol/L) and the overall mean glucose correlated with HbA1c at all visits. There were no differences in CGM mean glucose or coefficient of variation between the age groups of 4 and <6, 6 and <8, and 8 and <10.

CONCLUSIONS

Suboptimal glycemic control is common in young children with T1D as reflected by glucose levels in the hyperglycemic range for much of the day. New approaches to reduce postprandial glycemic excursions and increase time in the normal range for glucose in young children with T1D are critically needed. Glycemic targets in this age range should be revisited.

Satisfaction with continuous glucose monitoring in adults and youths with Type 1 diabetes

AIMS

To describe satisfaction with continuous glucose monitoring in Type 1 diabetes; to correlate continuous glucose monitoring satisfaction scores with usage; and to identify common themes in perceived benefits and barriers of monitoring reported by adults, youths and the parents of youths in the Juvenile Diabetes Research Foundation continuous glucose monitoring trials.

METHODS

The Continuous Glucose Monitoring Satisfaction Scale questionnaire was completed after 6 months of monitoring. Participants also answered open-ended queries of positive and negative attributes of continuous glucose monitoring.

RESULTS

More frequent monitoring was associated with higher satisfaction for adults (n = 224), youths (n = 208) and parents of youths (n = 192) (all P < 0.001) in both the 'benefits' and 'hassles' sub-scales of the Continuous Glucose Monitoring Satisfaction Scale, but the greatest differences between the two groups involved scores on hassle items. Common barriers to monitoring use included insertion pain, system alarms and body issues; while common benefits included glucose trend data, opportunities to self-correct out-of-range glucose levels and to detect hypoglycaemia.

CONCLUSIONS

As frequent use of continuous glucose monitoring is associated with improved glycaemic control without increased hypoglycaemia it is important to overcome barriers, reinforce benefits and set realistic expectations for this technology in order to promote its more consistent and frequent use in individuals with Type 1 diabetes.

Treatment options for type 2 diabetes in adolescents and youth: a study of the comparative efficacy of metformin alone or in combination with rosiglitazone or lifestyle intervention in adolescents with type 2 diabetes

Despite the increased prevalence of type 2 diabetes mellitus (T2DM) in the pediatric population, there is limited information about the relative effectiveness of treatment approaches. This article describes the rationale and design of a National Institutes of Health-sponsored multi-site, randomized, parallel group clinical trial designed to test the hypothesis that aggressive reduction in insulin resistance early in the course of T2DM is beneficial for prolongation of glycemic control, as well as improvement in associated abnormalities and risk factors. Specifically, the trial compares treatment with metformin with two alternate approaches, one pharmacologic (combining metformin treatment with rosiglitazone) and one combining metformin with an intensive lifestyle intervention program. The Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) study recruits 800 patients over a 4-yr period and follows them for a minimum of 2 yr and maximum of 6 yr. Patients are 10-17 yr of age, within 2 yr of diagnosis of diabetes at the time of randomization, lack evidence of autoimmunity, and have sustained C-peptide secretion. The primary outcome is time to loss of glycemic control, defined as a hemoglobin A1c >8% for 6 consecutive months. Secondary outcomes include the effect of the alternative treatments on insulin secretion and resistance, body composition, nutrition, physical activity and fitness, cardiovascular risk monitoring, microvascular complications, quality of life, depression, eating pathology, and resource utilization. TODAY is the first large-scale, systematic study of treatment effectiveness for T2DM in youth. When successfully completed, this study will provide critical new information regarding the natural history of T2DM in youth, the benefits of initiating early aggressive treatment in these patients, and the efficacy of delivering an intensive and sustained lifestyle intervention to children with T2DM.

Microalbuminuria in pediatric obesity: prevalence and relation to other cardiovascular risk factors

BACKGROUND

Microalbuminuria (MA) has emerged as a strong predictor of cardiovascular (CV) events, even in nondiabetic adults. While the mechanisms behind this association remain to be established, most studies suggest that MA is the result of increased vascular leakage denoting endothelial dysfunction associated with early vasculopathy.

OBJECTIVE

To examine if a urine albumin creatinine ratio (UACR) in the microalbuminuric range is related to metabolic markers of CV risk in obese and pre-diabetic youth recruited from an obesity clinic.

METHODS

MA was defined as a UACR between 2.0 and 20 mg/mmol. Subjects with gross proteinuria (UACR>20 mg/mmol) were excluded from the study. Analyses were performed to assess the relationship of MA and markers of CV risk, including body mass index (BMI), % body fat, blood pressure (BP), lipid profile, inflammatory markers, insulin sensitivity indexes and degrees of oral glucose tolerance. MA was also correlated with risk factor constellations unique to the metabolic syndrome, a distinct CV risk entity.

RESULTS

Postchallenge alterations in glucose metabolism and overall loss in insulin sensitivity were strongly and positively correlated with the presence of MA (P = 0.002 and 0.01, respectively). Neither the metabolic syndrome nor any of the individual CV risk factors examined were associated with MA.

CONCLUSIONS

These data suggest that early glucose toxicity, as reflected by postchallenge elevations in plasma glucose even below the diagnostic cutoff for diabetes mellitus may contribute to the presence of MA. Whether MA is equally as predictive of CV disease in youth, as in adulthood, remains to be investigated.

Constant vigilance: mothers' work parenting young children with type 1 diabetes

Little is known about the experiences of mothers raising young children with type 1 diabetes. The purpose of this study was to describe the day-to-day experiences of mothers (N = 28) raising young children under 4 years of age with type 1 diabetes. Descriptive, naturalistic inquiry principles were used to interview subjects, as well as to manage and analyze the data. The mothers reported using the management behavior of constant vigilance. Their concerns about hypoglycemia and providing competent care reflected the interplay between their fears and profound sense of responsibility for managing the disease. Mothers reported having to learn the management behaviors and to occasionally adjust the day-to-day management when either severe hypoglycemia or developmental milestones occurred. Although mothers initially had feelings of incompetence with the care they provided, with time, they became very skilled. There were also reports of limited access to babysitting, child care, or respite services. The intensity of their constant vigilance associated with their concerns, responsibility, and lack of supports resulted in some mothers having physical and/or emotional problems. The findings of the study highlight the importance of identifying family and/or community resources that may provide mothers with support that could reduce some of the tremendous stress and burden of responsibility experienced after diagnosis of diabetes.

Elevated ambulatory blood pressure in 20 subjects with Williams syndrome

Previous studies report conflicting frequencies of hypertension in cohorts of patients with Williams syndrome (WS). We studied blood pressure (BP) in WS using 24-hour ambulatory BP monitoring. This technique reliably measures day- and nighttime BP in a subject's natural environment and provides better prognostic information on long-term risks of hypertension than casual BP determinations. Twenty WS subjects evaluated through a multidisciplinary WS clinic and 35 age and gender-matched controls were studied. We found that WS subjects had significantly higher ambulatory BP than controls. After controlling for age, sex, and weight, the diagnosis of WS added approximately 10 mmHg to mean daytime and nighttime BPs. Hypertension, as defined by elevated mean daytime BP, was present in 40% of WS subjects versus 14% of controls (P < 0.05); among the children studied this difference was even more dramatic with 46% of WS children versus 6% of control children classified as hypertensive (P = 0.01). We also demonstrated normal diurnal BP variation but no evidence of a "white coat" effect or increased BP variability. Interestingly, parental reporting of a history of infantile hypercalcemia was strongly associated with the presence of hypertension (P = 0.008). Our data demonstrate that both children and adults with WS have higher mean BP and higher frequency of hypertension than healthy controls. Thus, elevated BP readings in the office setting should not be dismissed but require more thorough assessment.

Coronary artery disease in diabetic pregnancies

Severe vascular complications of diabetes mellitus include myocardial infarction and when this occurs during pregnancy it is associated with a high risk of maternal mortality. In the absence of myocardial infarction, information is unavailable on pregnancy outcome in diabetic patients with severe coronary artery disease or with prior coronary artery bypass graft. Such a case is presented together with a review of the literature.

Effect of growth hormone on oral glucose tolerance and circulating metabolic fuels in man

We infused growth hormone into normal subjects in doses that raised circulating hormone to levels (30-35 ng/ml) similar to those seen during stress. Growth hormone excess failed to alter fasting glucose and somatomedin concentrations. However, non-esterified fatty acids and ketones increased by 50% (p less than 0.05) and 120% (p less than 0.01), respectively, despite 35% higher plasma insulin concentrations. When oral glucose was ingested 5 h after initiating the growth hormone infusion, plasma glucose rose by 2-2.5 mmol/l above control (saline infusion) values and the area under the glucose curve increased twofold (p less than 0.005). This occurred in the face of twofold higher insulin levels and normal suppression of glucagon. Growth hormone also did not affect the hyperglycaemic response to a combined infusion of cortisol, glucagon and adrenaline, but accentuated the rise in non-esterified fatty acids, ketones, and insulin caused by these hormones. Our data suggest that growth hormone excess rapidly produces insulin antagonistic effects that may contribute to stress-induced glucose intolerance and lipolysis, even though fasting glucose levels remain unchanged.

Insulin binding and insulin sensitivity in isolated growth hormone deficiency

125I-insulin binding to monocytes was examined in five children and one adult with isolated growth hormone deficiency before and after three to 12 weeks of growth hormone treatment, and in eight controls. Before treatment, mean plasma glucose was 15 mg per deciliter below controls, and plasma insulin was reduced by 40 per cent. Insulin binding to monocytes was 70 per cent greater than controls (P less than 0.005). Insulin-mediated glucose uptake (determined in the adult patient) was 25 per cent greater than mean control levels. After treatment, plasma glucose rose to control levels, plasma insulin increased to 75 per cent above controls (P less than 0.01), and insulin binding fell to 50 per cent below controls (P less than 0.01). Insulin-mediated glucose uptake fell to 30 per cent below the mean control rate. Insulin binding increases in growth hormone deficiency and falls after treatment. These changes may contribute to alterations in insulin sensitivity accompanying altered growth hormone availability.

Influence of glucagon replacement on the hyperglycemic and hyperketonemic response to prolonged somatostatin infusion in normal man

Somatostatin was infused for 6 h into seven normal subjects with and without a replacement dose of glucagon. The addition of glucagon to somatostatin resulted in a 30-40% rise in plasma glucagon, whereas plasma insulin declined by 40-50% in both treatment groups. Plasma glucose and glucose production initially increased 2-fold with glucagon replacement, and subsequently declined by 2-3 h to levels comparable to those observed with somatostatin alone. After 6 h plasma glucose and glucose kinetics were no different whether or not glucagon was present. The rise in blood ketones after somatostatin was not exaggerated by glucagon replacement. We conclude that glucagon lack is not a modifying factor in the late hyperglycemic and hyperketonemic response to prolonged infusions of somatostatin.