Clinical and biochemical predictors of increased carotid intima-media thickness in overweight and obese adolescents with type 2 diabetes

Does Aerobic plus Machine-Assisted Resistance Training Improve Vascular Function in Type 2 Diabetes? A Systematic Review and Meta-Analysis of Randomized Controlled Trials with Trial Sequential Analysis

Type 2 diabetes mellitus (T2DM) is a chronic disease characterized by hyperglycemia, insulin resistance, and pancreatic B cell dysfunction. Hyperglycemia can cause several complications, including nephrological, neurological, ophthalmological, and vascular complications. Many modalities, such as medication, physical therapies, and exercise, are developed against vascular disorders. Among all exercise forms, aerobic plus machine-assisted resistance training is widely applied. However, whether this intervention can significantly improve vascular conditions remains controversial. In this study, an electronic search was processed for the Pubmed, Embase, and Cochrane libraries for randomized controlled trials (RCTs) comparing the efficacy of aerobic plus machine-assisted resistance training with no exercise (control) on patients with T2DM. Pulse wave velocity (PWV), the index of arterial stiffness, was chosen as primary outcome. The reliability of the pooled outcome was tested by trial sequential analysis (TSA). Secondary outcomes included systolic blood pressure (SBP) and hemoglobin A1c (HbA1c). Finally, five RCTs with a total of 328 patients were included. Compared with control, aerobic plus machine-assisted resistance training failed to provide significant improvement on PWV (MD −0.54 m/s, 95% CI [−1.69, 0.60], p = 0.35). On the other hand, TSA indicated that this results till needs more verifications. Additionally, this training protocol did not significantly decrease SBP (MD −1.05 mmHg, 95% CI [−3.71, 1.61], p = 0.44), but significantly reduced the level of HbA1c (MD −0.55%, 95% CI [−0.88, −0.22], p = 0.001). In conclusion, this meta-analysis failed to detect a direct benefit of aerobic plus machine-assisted resistance training on vascular condition in T2DM population. Yet the improvement in HbA1c implied a potential of this training method in mitigating vascular damage. More studies are needed to verify the benefit.

The Relationship Between Lipoproteins and Insulin Sensitivity in Youth With Obesity and Abnormal Glucose Tolerance

CONTEXT

Youth with obesity and abnormal glucose tolerance have an increased risk for atherosclerosis but the relative contributions of insulin resistance and hyperglycemia to dyslipidemia and the development of subclinical atherosclerosis are unknown.

OBJECTIVE

This work aims to determine the association between insulin resistance, dyslipidemia, and carotid intimal thickness (cIMT) in adolescents with normal and abnormal glucose tolerance.

METHODS

An observational cohort study in 155 youth: 44 obese insulin sensitive (OIS; fasting insulin ≤ 20 µM/mL, body mass index [BMI] ≥ 95th percentile), 35 obese insulin resistant (OIR; fasting insulin > 20 µM/mL, BMI ≥ 95th percentile), 34 obese abnormal glucose tolerant (AGT; BMI ≥ 95th percentile), and 42 Lean (BMI 5th-85th percentile). Lipids, lipoprotein particle size and concentration (-P), insulin sensitivity (SI an intravenous glucose test), and CMIT were compared using linear models adjusted for age, race/ethnicity, biological sex, and Tanner stage. Lipid/lipoprotein profile and CMIT were reevaluated in a subset after 2 years.

RESULTS

Compared to OIS and Lean, OIR and AGT had elevated triglycerides and low high-density lipoprotein cholesterol (HDL-C) but similar total cholesterol and low-density lipoprotein cholesterol (LDL-C). Among OIS, OIR, AGT, lower SI was associated with atherogenic lipids (higher triglycerides, LDL-C, non-HDL-C, and lower HDL-C) and lipoproteins (higher total LDL-P and small HDL-P, and lower large HDL-P). There was a steeper decline in the association of SI with HDL-C and large HDL-P in AGT compared with OIR and OIS. cIMT was comparable across groups and inversely correlated with SI, with no change after 2 years.

CONCLUSION

Among youth with obesity, insulin resistance was associated with an atherogenic lipoprotein/lipid profile and cIMT, regardless of glucose tolerance status. Insulin resistance in AGT youth was associated with a shift to smaller HDL-P compared to normoglycemic youth with obesity. Alterations in HDL-P metabolism may be early adverse manifestations of hyperglycemia in youth with obesity.

Longitudinal changes in vascular stiffness and heart rate variability among young adults with youth-onset type 2 diabetes: results from the follow-up observational treatment options for type 2 diabetes in adolescents and youth (TODAY) study

AIMS

(1) To describe changes in arterial stiffness and heart rate variability (HRV) over a 5-year interval, (2) examine changes by sex and race-ethnicity, and (3) evaluate the risk factors associated with the longitudinal changes in arterial stiffness and HRV.

METHODS

Participants with youth-onset type 2 diabetes enrolled in the observational follow-up phase of the Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) clinical trial had arterial stiffness [(pulse wave velocity, augmentation index, brachial distensibility] and six indices of HRV measured 5 years apart. Multivariable linear regression models assessed risk factors associated with changes in the outcomes over time.

RESULTS

At initial vascular assessment, the 304 participants were a mean age of 21 years, 34% male, and had a mean diabetes duration of 8 years. In more than half the cohort pulse wave velocity, augmentation index and HRV increased over 5 years (p<0.01). Brachial distensibility did not change. There were no differences in the 5-year change by race/ethnicity except for a single HRV measure, where non-Hispanic Blacks had greater worsening of parasympathetic function compared to non-Hispanic Whites, p = 0.008. Blood pressure was related to greater worsening in augmentation index and pulse wave velocity. Higher hemoglobin A1c over time was related to worsening pulse wave velocity and HRV.

CONCLUSIONS

Arterial stiffness and HRV worsened over 5 years. Blood pressure and glycemic control may be potential targets to influence adverse changes in arterial stiffness and HRV in young adults with youth-onset type 2 diabetes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00081328.

Contribution of Type 2 Diabetes Mellitus to Subclinical Atherosclerosis in Subjects with Morbid Obesity

INTRODUCTION

Type 2 diabetes mellitus (T2DM) and obesity are both related to increased risk of cardiovascular disease and mortality. Early atherosclerotic vascular changes can be detected by non-invasive tests like carotid artery intima-media thickness (cIMT) and pulse wave velocity (PWV). Both cIMT and PWV are significantly impaired in T2DM patients and in obese patients, but the additional effect of T2DM on these vascular measurements in obese subjects has not been evaluated.

METHODS

Two hundred morbidly obese patients with or without T2DM were enrolled in a prospective cohort study and underwent extensive laboratory testing, including cIMT and PWV measurements. The cohort was divided into a group with and a group without T2DM.

RESULTS

Within this cohort, 43 patients (21.5%) were diagnosed with T2DM. These patients were older and had more often (a history of) hypertension as compared to patients without T2DM. HbA1c levels were significantly increased, while LDL cholesterol was significantly lower and the use of statins higher than in non-diabetic participants. cIMT and PWV were significantly increased in subjects suffering from T2DM. The variability in cIMT and PWV was related to differences in age and systolic blood pressure, but not to the presence of T2DM.

CONCLUSION

While T2DM negatively affects the vasculature in morbid obesity, hypertension and age seem to be the major risk factors, independent from the presence of T2DM.

CLINICAL TRIAL REGISTRATION

Dutch Trial Register NTR5172 .

Effects of combined training with different intensities on vascular health in patients with type 2 diabetes: a 1-year randomized controlled trial

Background

Exercise, when performed on a regular basis, is a well-accepted strategy to improve vascular function in patients with type 2 diabetes. However, the exercise intensity that yields maximal adaptations on structural and functional indices in patients with type 2 diabetes remains uncertain. Our objective was to analyze the impact of a 1-year randomized controlled trial of combined high-intensity interval training (HIIT) with resistance training (RT) vs. a combined moderate continuous training (MCT) with RT on structural and functional arterial indices in patients with type 2 diabetes.

Methods

Patients with type 2 diabetes (n = 80) were randomized into an exercise intervention with three groups: control, combined HIIT with RT and combined MCT with RT. The 1-year intervention had 3 weekly exercise sessions. High-resolution ultrasonography of the common carotid artery and central and peripheral applanation tonometry were used to assess the changes in structural and functional arterial indices. Generalized estimating equations were used to model the corresponding outcomes.

Results

After adjusting the models for sex, baseline moderate-to-vigorous physical activity, and mean arterial pressure changes, while using the intention-to-treat analysis, a significant interaction was observed on the carotid intima-media thickness (cIMT) for both the MCT (β = − 4.25, p < 0.01) and HIIT group (β = − 3.61, p < 0.01). However, only the HIIT observed favorable changes from baseline to 1-year on peripheral arterial stiffness indices such as carotid radial arterial pulse wave velocity (β = − 0.10, p = 0.044), carotid to distal posterior tibial artery pulse wave velocity (β = − 0.14, p < 0.01), and on the distensibility coefficient (β = − 0.00, p < 0.01). No effect was found for hemodynamic variables after the intervention.

Conclusions

Following a 1-year intervention in patients with type 2 diabetes, both the MCT and HIIT group reduced their cIMT, whereas only the HIIT group improved their peripheral arterial stiffness indices and distensibility coefficient. Taken together, HIIT may be a meaningful tool to improve long-term vascular complications in type 2 diabetes.

Trial registration clinicaltrials.gov ID: NCT03144505

Youth-Onset Type 2 Diabetes and the Developing Brain

PURPOSE OF REVIEW

This review describes the literature evaluating the potential adverse effects of youth-onset type 2 diabetes on the developing brain. A summary of recently published articles and the current state of knowledge are covered succinctly in this manuscript.

RECENT FINDINGS

Current literature suggests both cognitive and brain structural differences are found in youth with type 2 diabetes. Studies have shown poorer scores in a number of neurocognitive domains, particularly in areas of executive functioning and memory. Additionally, imaging studies have found differences in brain gray matter volume, white matter volume, and microstructural integrity. These findings are largely consistent with the adult literature. Youth with type 2 diabetes demonstrate lower cognitive scores and structural brain differences. Although causality has not yet been established, these findings are important because these individuals are still undergoing neurodevelopmental maturation.

Prevalence of arterial stiffness in adolescents with type 2 diabetes in the TODAY cohort: Relationships to glycemic control and other risk factors

AIMS

We aimed to determine the prevalence of arterial stiffness in young adults with youth-onset type 2 diabetes who previously participated in the TODAY clinical trial and whether arterial stiffness is influenced by their prior diabetes treatment assignment or glycemic control.

METHODS

We measured arterial stiffness by femoral, radial, and foot pulse wave velocity (PWV), augmentation index (AIx), and brachial distensibility (BrachD) in 453 TODAY participants (age 20.8 ± 2.5 years, diabetes duration 7.6 ± 1.5 years, 36.4% male, BMI 36.7 ± 8.2 kg/m²) at a mean of 7.6 years post-randomization. Increased arterial stiffness in TODAY youth was defined compared with data from lean controls. We assessed whether glycemic control over time or diabetes treatment in TODAY was associated with arterial stiffness.

RESULTS

Arterial stiffness was identified in up to 50% of TODAY participants. Prior diabetes treatment assignment was not associated with higher arterial stiffness. Glycemic control over time was associated with PWV radial and foot only. Age, race-ethnicity, sex, higher blood pressure and BMI were also associated with higher arterial stiffness.

CONCLUSIONS

Nearly half of TODAY youth have increased arterial stiffness. Targeting blood pressure and perhaps obesity and glycemic control may positively impact arterial health in adolescents with type 2 diabetes.

TRIAL REGISTRATION

ClinicalTrials.govNCT00081328.

Vascular and Endothelial Function in Youth with Type 2 Diabetes Mellitus

PURPOSE OF REVIEW

This review aims to discuss the burden of type 2 diabetes in youth and summarize the studies that have utilized noninvasive techniques to assess early vascular disease in youth with type 2 diabetes.

RECENT FINDINGS

Noninvasive imaging modalities provide researchers with tools to investigate the vasculature in adolescents with type 2 diabetes. The data published to date consistently show adolescents with type 2 diabetes have greater vascular thickness and stiffness and worse endothelial function compared to their obese and lean peers. As the prevalence of type 2 diabetes continues to increase adolescent youth, there is concern adolescents with type 2 diabetes are at risk to develop early onset cardiovascular disease and complications. Future studies need to address treatments that have the potential to improve or reverse vascular dysfunction and decrease the rate of cardiovascular disease and complications.

Comparison of Antidiabetic Medications during the Treatment of Atherosclerosis in T2DM Patients

Type 2 diabetes is often associated with arterial atherosclerosis in large blood vessels. We set out to elucidate whether commonly used antidiabetic drugs metformin, sitagliptin, and pioglitazone will reduce atherosclerosis in T2DM patients. We enrolled 176 individuals with type 2 diabetes, which were divided into four treatment groups according to different oral drugs: metformin alone, sitagliptin alone, pioglitazone alone, or combination of metformin and sitagliptin. We assessed changes in glycometabolism, lipid metabolism, cytokine released, and carotid artery intima-media thickness as the readout for improvement in atherosclerosis. HbA1c levels were significantly decreased in all treatment groups (p < 0.05), and FBG levels were also decreased in metformin and combined groups (p < 0.05). In addition, we found IL-6 levels significantly decreased in all treatment groups (p < 0.05). Treatment with pioglitazone showed a significant increase in BMI, HDL, and ADPN levels (p < 0.05). We also observed a significant decrease in NHDL levels in the combined treatment group (p < 0.05). Our data revealed that in addition to hypoglycemic properties of metformin, sitagliptin, and pioglitazone, these drugs also have the potential to promote an anti-inflammatory response. Therefore, combination therapy may be more beneficial for reducing atherosclerosis in patients with type 2 diabetes. The clinical trial is registered with ChiCTR-ORC-17010835.

Adiposity has no direct effect on carotid intima-media thickness in adolescents and young adults: Use of structural equation modeling to elucidate indirect & direct pathways

BACKGROUND

Carotid intima-media thickness (cIMT) is associated with CV events in adults. Thicker cIMT is found in youth with CV risk factors including obesity. Which risk factors have the most effect upon cIMT in youth and whether obesity has direct or indirect effects is not known. We used structural equation modeling to elucidate direct and indirect pathways through which obesity and other risk factors were associated with cIMT.

METHODS

We collected demographics, anthropometrics and laboratory data on 784 subjects age 10-24 years (mean 18.0 ± 3.3 years). Common, bulb and internal carotid cIMT were measured by ultrasound. Multivariable regression analysis was performed to assess independent determinants of cIMT. Analyses were repeated with structural equation modeling to determine direct and indirect effects.

RESULTS

Multivariable regression models explained 11%-22% of variation of cIMT. Age, sex and systolic blood pressure (BP) z-score were significant determinants of all cIMT segments. Body mass index (BMI) z-score, race, presence of type 2 diabetes mellitus (T2DM), hemoglobin A1c (HbA1c) and non-HDL were significant for some segments (all p = 0.05). The largest direct effect on cIMT was age (0.312) followed by BP (0.228), Blood glucose control (0.108) and non-HDL (0.134). BMI only had a significant indirect effect through blood glucose control, BP & non-HDL. High sensitivity C-reactive protein (CRP) had a small indirect effect through blood glucose control (all p = 0.05).

CONCLUSIONS

Age and BP are the major factors with direct effect on cIMT. Glucose and non-HDL were also important in this cohort with a high prevalence of T2DM. BMI only has indirect effects, through other risk factors. Traditional CV risk factors have important direct effects on cIMT in the young, but adiposity exerts its influence only through other CV risk factors.

HDL function and subclinical atherosclerosis in juvenile idiopathic arthritis

BACKGROUND

Increasing evidence suggests that inflammation adversely impacts the protective properties of high-density lipoproteins (HDL) and progression of atherosclerosis. The impact of early chronic inflammatory conditions on HDL function and vascular risk has not been well investigated.

METHODS

We compared measures of HDL particle distribution and functionality, in addition to measures of carotid intima-medial thickness (cIMT) in patients with juvenile idiopathic arthritis (JIA) and age matched controls.

RESULTS

JIA patients demonstrated lower levels of HDL cholesterol [47.0 (40.0, 56.0) vs. 56.0 (53.0, 61.0) mg/dL, P=0.04], total HDL [29.5 (27.9, 32.3) vs. 32.9 (31.6, 36.3) mg/dL, P=0.05] and large HDL [5.1 (3.7, 7.3) vs. 8.0 (6.7, 9.7) mg/dL, P=0.04] particles. In association JIA patients demonstrated greater cholesterol efflux mediated via ATP binding cassette A1 (ABCA1) [17.3% (12.8, 19.7) vs. 10.0% (5.8, 16.0), P=0.05] and less efflux mediated via ATP binding cassette G-1 (ABCG1) [3.2% (2.0, 3.9) vs. 4.8% (3.5, 5.8), P=0.01] and SR-B1 [6.9% (6.0, 8.4) vs. 9.1% (8.6, 10.2), P=0.002] compared with controls. Exposure of macrophages to serum from JIA patients resulted in a smaller increase in mRNA expression of ABCA1 (2.0±0.95 vs. 7.1±5.7 fold increase, P=0.01) and greater increases in expression of ABCG1 [1.4 (0.9, 1.5) vs. 0.8 (0.7, 1.1) fold increase, P=0.04] and SR-B1 (1.3±0.47 vs. 0.7±0.3 fold increase, P=0.001) compared with controls. Arylesterase (128.9±27.6 vs. 152.0±45.2 umoles/min/mL, P=0.04) activity and endothelial cell migration (491.2±68.9 vs. 634.2±227.4 cells/field, P=0.01) were less in JIA patients. No differences in cIMT were observed between JIA patients and controls.

CONCLUSIONS

The presence of JIA was associated with alterations in HDL particle distribution, cholesterol efflux and non-lipid transporting activities. The ultimate implication of these findings for cardiovascular risk requires further investigation.

Influence of physical activity and gender on arterial function in type 2 diabetes, normal and impaired glucose tolerance

To determine whether Nordic walking improves cardiovascular function in middle-aged women and men, we included 121 with normal glucose tolerance, 33 with impaired glucose tolerance and 47 with Type 2 diabetes mellitus in a randomized controlled study. The intervention group added Nordic walking 5 h/week for 4 months to their ordinary activities. Aortic pulse wave velocity, aortic augmentation index, stiffness index, reflection index, intima-media thickness in the radial and carotid arteries, echogenicity of the carotid intima-media and systemic vascular resistance were measured. While baseline blood pressure did not differ by gender or diagnosis, aortic augmentation index was found to be higher in women in all groups. Vascular function was unchanged with intervention, without differences by gender or diagnosis. In conclusion, 4 months of Nordic walking is an insufficient stimulus to improve vascular function. Future studies should consider hard endpoints in addition to measures of vascular health, as well as larger population groups, long-term follow-up and documented compliance to exercise training.

Metabolic diseases and sex hormone levels affect differently in the development of cardiovascular and cerebrovascular diseases in elderly males

OBJECTIVE

This single-centre cross-sectional study aimed to investigate the metabolic and gonadal risk factors of vascular diseases in elderly males.

METHODS

After screening, 337 subjects aged 60-90 were found to be qualified. Odds ratios (ORs) in cross-table analyses and exp(B) in logistic regression analyses were used to evaluate the vascular risk of dependent factors. R(2) of logistic regression equation was used to estimate the goodness-of-fit of vascular diseases logistic regression models.

RESULTS

Hypertension increased the risk of cardiovascular disease (CAVD) in elderly men approximately 3-fold. The number of metabolic diseases also correlated with incremental risks of CAVD; presence of one abnormality approximately increases the risk approximately 62%. Cerebrovascular disease (CEVD) development was closely associated with both metabolic syndrome and sex hormone levels; their explanation effects of single action and combined action were 13.2%, 12.55% and 28.5%. C-peptide might be the underlying mechanism of the metabolic syndrome's effect on CEVD. C-peptide = 2.43 U/L and FE(2) = 0.66 were the tangent points in receiver operating characteristic (ROC) analyses.

CONCLUSIONS

Metabolic diseases and sex hormones play different roles in the development of CAVD and CEVD, the methods for vascular protection in elderly men should be promoted differently according to the their risks of CAVD and CEVD.

Correlation between biopterin levels and intimal-media thickness in type-2 diabetic hypertensive patients

Background

Biopterins have a crucial role in the function of nitric oxide synthase, uncoupling of the enzyme leads to endothelial dysfunction and vascular damage, The aim of this study was to evaluate the relationship between the levels of biopterins with carotid intima-media thickness (CIMT) in hypertensive type-2 diabetic patients.

Methods

We studied 30 hypertensive type-2 diabetic patients and 30 normotensive non-diabetic age-matched subjects, in whom biopterins levels were measured by reverse phase high performance liquid chromatography with fluorescence detection. Additionally, the CIMT of both the common and internal carotid arteries was measured. The levels of biopterins and CIMT were correlated using the Pearson correlation coefficient test.

Results

We did not find a significantly correlation between biopterins levels and CIMT. However, we found a significantly inverse correlation between the BH4/BH2 ratio and the CIMT in patients (r = -0.54, p < 0.01). A multiple regression analysis revealed that the CIMT correlated significantly and independently with the BH4/BH2 ratio.

Conclusion

Our results suggest that the BH4/BH2 ratio seems to be a better marker of vascular disease than biopterin levels.

Effects of curcumin on brain-derived neurotrophic factor levels and oxidative damage in obesity and diabetes

We evaluated the effects of curcumin treatment on protein oxidation (PO), lipid peroxidation (LP) and brain-derived neurotrophic factor (BDNF) levels in the hippocampus and frontal cortex (FC) of diabetic db/db mice (DM) and in sera of obese humans. Thus, DM were treated daily with 50 mg/kg of curcumin during an 8-week period. Obese human were treated daily with 500 and 750 mg of curcumin that was administered orally for 12 weeks; BDNF, PO and LP levels in sera were determined at in weeks 0, 2, 6 and 12 of treatment. BDNF levels decreased in hippocampus and FC of DM as compared with untreated wild-type mice. Curcumin improved or restored BDNF levels to normal levels in DM, but curcumin did not have any effect on BDNF levels in sera of obese humans. In hippocampus and FC of DM, hyperglycaemia and curcumin did not have effect on LP levels. Hyperglycaemia increased PO levels in hippocampus and FC, whereas curcumin decreased these levels in hippocampus but not in FC. In sera of obese humans, the 500-mg dose decreased LP levels in weeks 6 and 12 when compared with basal levels, but the 750-mg dose did not have any effect; both doses of curcumin decreased PO levels in weeks 2, 6 and 12 of treatment when compared with basal levels. Present results suggest a therapeutic potential of curcumin to decrease oxidation caused by obesity in humans and also show that curcumin restores BDNF levels in DM.

Correlation between levels of circulating adipokines and adiponectin/resistin index with carotid intima-media thickness in hypertensive type 2 diabetic patients

BACKGROUND

Hypoadiponectinemia and hyperresistinemia are associated with cardiovascular disease. The increase in the carotid intima-media thickness (CIMT) assessed by B-mode ultrasound has been directly associated with increased risk of myocardial infarction and stroke.

OBJECTIVE

To evaluate the correlation between adipokine levels with CIMT in hypertensive type 2 diabetic patients.

METHODS

Serum levels of adiponectin and resistin levels were measured by ELISA in 30 type 2 diabetic patients with never-treated hypertension and in age-matched healthy controls. The CIMT (B-mode color imaging of extracranial carotid arteries using high-resolution ultrasound) was also obtained. The relationship between adipokine levels and the adiponectin/resistin index with the CIMT was assessed by the Pearson correlation coefficient test.

RESULTS

Adiponectin was lower (p < 0.05), and resistin higher (p < 0.01) in patients than in controls, CIMT correlated positively with resistin (R = 0.45, p < 0.02) and the adiponectin/resistin index (R = 0.58, p < 0.001), but not with adiponectin levels (r = -0.11, p > 0.1) in patients. Whereas only adiponectin levels correlated - negatively - with CIMT (r = -0.39, p < 0.02) in controls.

CONCLUSION

Our results shown that the adiponectin/resistin index seems to be more strongly associated with atherosclerosis than adipokine levels, and may be used as a reliable marker of cardiovascular risk in type 2 diabetic hypertensive patients.

Early signs of atherosclerosis are associated with insulin resistance in non-obese adolescent and young adults with type 1 diabetes

Background

Patients with type 1 diabetes have a substantial risk of developing cardiovascular complications early in life. We aimed to explore the role of insulin sensitivity (S_i) as an early factor of atherosclerosis in young type 1 diabetes vs. non-diabetic subjects.

Methods

Forty adolescent and young adult individuals (20 type 1 diabetics and 20 non-diabetics), age 14–20 years, without characteristics of the metabolic syndrome, participated in this cross-sectional study. After an overnight fast, S_i was measured by hyperinsulinemic euglycemic clamp (40 mU/m²) and calculated by glucose infusion rate (GIR). Carotid intima-media thickness (cIMT) was measured in the common carotid artery with high-resolution ultrasonography. Risk factors of atherosclerosis (Body mass index [BMI], waist circumference, systolic blood pressure [sBP], triglycerides, low HDL-cholesterol and HbA_1c) were also investigated.

Results

cIMT was increased (0.52 ± 0.1 vs. 0.47 ± 0.1 mm, P < 0.01), whereas GIR was decreased (5.0 ± 2.1 vs. 7.1 ± 2.2 mg/kg/min, P < 0.01) in type 1 diabetics vs. non-diabetics. The differences in cIMT were negatively associated with S_i (r = −0.4, P < 0.01) and positively associated with waist circumference (r = 0.34, P = 0.03), with no such associations between BMI (r = 0.15, P = 0.32), sBP (r = 0.09, P = 0.58), triglycerides (r = 0.07, P = 0.66), HDL-cholesterol (r = 0.10, P = 0.55) and HbA_1c (r = 0.24, P = 0.13). In a multivariate regression model, between cIMT (dependent) and group (explanatory), only adjustment for S_i affected the significance (ß = 0.08, P = 0.11) vs. (ß = 0.07, P < 0.01) for the whole model. No interaction between cIMT, groups and S_i was observed.

Conclusions

cIMT is increased and associated with insulin resistance in adolescent, non-obese type 1 diabetic subjects. Although, no conclusions toward a causal relationship can be drawn from current findings, insulin resistance emerges as an important factor reflecting early signs of atherosclerosis in this small cohort.

Impact of metabolic syndrome on cognition and brain: a selected review of the literature

Metabolic syndrome (MetS), a clustering of risk factors for type 2 diabetes mellitus and cardiovascular disease, has been associated with cognitive dysfunction and brain abnormalities. This review describes the literature on the impact of MetS on brain and cognition and suggests directions for future research. A literature search for reports of MetS and cognition and brain imaging was conducted for both nonelderly adults and adolescents. No studies were found describing MetS and brain or cognition among adolescents; therefore, we also included studies investigating individual components of MetS in this age group. Most studies found associations between MetS and cognitive dysfunction. Multiple cognitive domains were affected by MetS in adults. In adolescents, the majority of findings were in executive functioning. Brain imaging literature in adults implicated MetS in ischemic stroke, white matter alterations, and altered brain metabolism. For adolescents, individual MetS factors were linked to volume losses in the hippocampus and frontal lobes. MetS negatively impacts cognitive performance and brain structure. Potential explanatory models include impaired vascular reactivity, neuroinflammation, oxidative stress, and abnormal brain lipid metabolism. We posit that insulin resistance-associated impairment in cerebrovascular reactivity is an important mechanism underlying brain deficits seen in MetS.