Hypoglycemia, but not glucose variability, relates to vascular function in children with type 1 diabetes

Cardiovascular disease in type 1 diabetes, an underestimated danger: Epidemiological and pathophysiological data

Cardiovascular disease (CV) is a common complication of type 1 diabetes (T1D) and a leading cause of death. T1D patients are more likely to develop CV disease (CVD) early in life and show a reduction of life expectancy of at least 11 years. Patients with a young age of T1D onset have a substantially higher CV risk. The reasons for increased atherosclerosis in T1D patients are not entirely explained. In addition to the typical CV risk factors, long-term hyperglycemia has a significant impact by inducing oxidative stress, vascular inflammation, monocyte adhesion, arterial wall thickening and endothelial dysfunction. Additionally, CVD in T1D is also associated with nephropathy. However, CVD risk is still significantly increased in T1D patients, in good glycemic control without additional CV risk factors, indicating the involvement of supplementary potential factors. By increasing oxidative stress, vascular inflammation, and endothelial dysfunction, hypoglycemia and glucose variability may exacerbate CVD. Moreover, significant qualitative and functional abnormalities of lipoproteins are present in even well-controlled T1D patients and are likely to play a role in the development of atherosclerosis and the promotion of CVD. According to recent research, immune system dysfunction, which is typical of auto-immune T1D, may also promote CVD, likely via inflammatory pathways. In addition, T1D patients who are overweight or obese exhibit an additional CV risk due to pathophysiological mechanisms that are similar to those seen in T2D.

Low Blood Glucose Index Associated with Cardiovascular Events in Diabetic Hemodialysis Patients

INTRODUCTION

Blood glucose monitoring was vitally important in diabetic kidney disease (DKD) patients for preventing complications and improving survival rates. The associations between glycemic variability and blood biochemical indicators were underestimated in patients with DKD undergoing hemodialysis. Therefore, we primarily aimed to investigate the glycemic variability and 1-year risk of cardiovascular disease events in diabetic hemodialysis patients. And we secondarily aimed to explore the association between glycemic variability and blood biochemical indicators.

METHODS

In total, 27 patients were included in the final analysis. Continuous glucose monitoring (CGM) was used to evaluate glucose variability for 14 days. Patients were divided into two groups by the cutoff level of time in range (TIR; >70% or ≤70%). The three-point major adverse cardiovascular event (3P MACE) was recorded within 1 year.

RESULTS

After 1 year of follow-up, 4 patients in the high-TIR group and 3 patients in the low-TIR group had 3p MACE. Higher low blood glucose index (LBGI) level in diabetic hemodialysis patients increased the risk of 3p MACE outcomes (HR = 2.37, p = 0.018). And the level of albumin was positively associated with LBGI (β = 0.51, p = 0.036). The plasma levels of albumin, glycosylated hemoglobin, and hemoglobin were positively associated with other CGM parameters.

CONCLUSION

LBGI during 14 days was positively associated with the risk of cardiovascular events in diabetic hemodialysis patients.

Risk factors for pre-clinical atherosclerosis in adolescents with type 1 diabetes

AIMS

To assess whether, besides "traditional" risk factors, overall oxidative stress, oxidized lipoproteins, and glycemic variability are associated with early macro-vascular damage in type 1 diabetes (T1D).

METHODS

In 267 children/adolescents with T1D (130 girls, age 9.1-23.0 years) we evaluated: derivatives of reactive oxygen metabolites [d-ROMs], serum total antioxidant capacity [TAC] and oxidized LDL-cholesterol [oxLDL]; markers of early vascular damage (Lipoprotein-associated phospholipase A2 [Lp-PLA2], z-score of carotid intima-media thickness [z-cIMT] and carotid-femoral pulse wave velocity [z-PWV]); CGM metrics of four weeks preceding the visit, central systolic/diastolic blood pressures (cSBP/cDBP), and HbA1c, z-score of BP (z-SBP/z-DBP) and circulating lipids longitudinally collected since T1D onset.. Three general linear models were built with z-cIMT, z-PWV adjusted for current cDBP, and Lp-PLA2 as independent variables.

RESULTS

The z-cIMT was associated with male gender (B = 0.491, η² = 0.029, p = 0.005), cSBP (B = 0.023, η² = 0.026, p = 0.008) and oxLDL (B = 0.022, η² = 0.022, p = 0.014). The z-PWV was associated with diabetes duration (B = 0.054, η² = 0.024, p = 0.016), daily insulin dose (B = 0.52, η² = 0.018, p = 0.045), longitudinal z-SBP (B = 0.18, η² = 0.018, p = 0.045) and dROMs (B = 0.003, η² = 0.037, p = 0.004). Lp-PLA2 was associated with age (B = 0.221, η² = 0.079, p = 3*10^-6), oxLDL (B = 0.081, η² = 0.050, p = 2*10^-4), longitudinal LDL-cholesterol (B = 0.031, η² = 0.043, p = 0.001) and male gender (B = -1.62, η² = 0.10, p = 1.3*10⁷).

CONCLUSIONS

Oxidative stress, male gender, insulin dose, diabetes duration and longitudinal lipids and blood pressure, contributed to the variance of early vascular damage in young patients with T1D.

Hyperglycemia and hypoglycemia exposure are differentially associated with micro- and macrovascular complications in adults with Type 1 Diabetes

AIMS

Evaluate the relationship between high and low exposure continuous glucose monitoring (CGM)-derived glucometrics and micro- and macrovascular complications in type 1 diabetes (T1D).

METHODS

Cross-sectional study in T1D without cardiovascular disease (CVD) and with ≥ 1 of the following: ≥40 years, diabetic nephropathy, or ≥ 10 years of diabetes duration with CVD risk factors. Glucometrics were obtained over 14 consecutive days: glucose management indicator (GMI) and proportion of time < 54 (TBR < 54), <70, 70-180 (TIR), >180 (TAR). Carotid plaque was evaluated by ultrasonography. Logistic regression models adjusted for age, sex, and other risk factors were constructed to test the independent associations with chronic complications.

RESULTS

We included 152 patients (54.6% men, 48.7 ± 10.0 years-old). Sixty-seven patients had plaque and n = 71 microvascular complications. TAR (OR 1.28 [1.09-1.51]) and GMI (OR 3.05 [1.46-6.36]) were directly associated with the presence of microvascular complications, while TIR had an inverse relationship (OR 0.79 [0.66-0.93]). TBR < 54 was directly associated with the presence of plaque, even after adjusting for 5-year mean HbA1c (OR 1.51 [1.07-2.13]).

CONCLUSIONS

High-glucose glucometrics were independently associated with microvascular complications. Only low-glucose exposure glucometrics was significantly associated with preclinical atherosclerosis. Our data support the role of hypoglycemia in the development of CVD in this population.

Complications of Diabetes and Metrics of Glycemic Management Derived From Continuous Glucose Monitoring

CONTEXT

Although glycated hemoglobin A1c is currently the best parameter used clinically to assess risk for the development of diabetes complications, it does not provide insight into short-term fluctuations in glucose levels. This review summarizes the relationship between continuous glucose monitoring (CGM)-derived metrics of glycemic variability and diabetes-related complications.

EVIDENCE ACQUISITION

PubMed and Embase databases were searched from January 1, 2010 to August 22, 2020, using the terms type 1 diabetes, type 2 diabetes, diabetes-related microvascular and macrovascular complications, and measures of glycaemic variability. Exclusion criteria were studies that did not use CGM and studies involving participants who were not diabetic, acutely unwell (post stroke, post surgery), pregnant, or using insulin pumps.

EVIDENCE SYNTHESIS

A total of 1636 records were identified, and 1602 were excluded, leaving 34 publications in the final review. Of the 20 852 total participants, 663 had type 1 diabetes (T1D) and 19 909 had type 2 diabetes (T2D). Glycemic variability and low time in range (TIR) showed associations with all studied microvascular and macrovascular complications of diabetes. Notably, higher TIR was associated with reduced risk of albuminuria, retinopathy, cardiovascular disease mortality, all-cause mortality, and abnormal carotid intima-media thickness. Peripheral neuropathy was predominantly associated with standard deviation of blood glucose levels (SD) and mean amplitude of glycemic excursions (MAGE).

CONCLUSION

The evidence supports the association between diabetes complications and CGM-derived measures of intraday glycemic variability. TIR emerged as the most consistent measure, supporting its emerging role in clinical practice. More longitudinal studies and trials are required to confirm these associations, particularly for T1D, for which there are limited data.

Post-Bariatric Hypoglycemia Is Associated with Endothelial Dysfunction and Increased Oxidative Stress

Post-bariatric hypoglycemia (PBH) is a potentially serious complication that may occur after bariatric surgery. Recurrent hypoglycemia may exert detrimental effects on vascular function. The aim of the present study was to evaluate endothelial function and oxygen reactive compounds in patients who experience PBH compared with controls. We performed a cross-sectional study on subjects with PBH (HYPO) and those without (NO-HYPO), detected by seven-day continuous glucose monitoring (CGM) performed at least twelve months after bariatric surgery. We enrolled 28 post-bariatric subjects (17.9% males, mean age 40.6 ± 10.7 years), with 18 in the HYPO group and 10 in the NO-HYPO group. In the two groups, we measured brachial artery flow-mediated dilation (FMD), oxidized low-density lipoproteins (oxLDL) and reactive oxygen metabolites (D-ROMs). The HYPO group had significantly lower FMD values than the NO-HYPO group (3.8% ± 3.0 vs. 10.5% ± 2.0, p < 0.001). A significant correlation was found between FMD and the time spent in hypoglycemia (rho = −0.648, p < 0.001), the number of hypoglycemic events (rho = −0.664, p < 0.001) and the mean glucose nadir (rho = 0.532, p = 0.004). The HYPO group showed significantly higher levels of D-ROMs (416.2 ± 88.7 UCARR vs. 305.5 ± 56.3 UCARR, p < 0.001) and oxLDLs (770.5 ± 49.7 µEq/L vs. 725.1 ± 51.6 µEq/L, p = 0.035) compared to the NO-HYPO group. In the multiple linear regression analysis, hypoglycemia independently predicted FMD values (β = −0.781, p < 0.001), D-ROMs (β = 0.548, p = 0.023) and oxLDL levels (β = 0.409, p = 0.031). PBH is associated with impaired endothelial function accompanied by increased oxidative stress.

Relationship Between Time in Range, Glycemic Variability, HbA1c, and Complications in Adults With Type 1 Diabetes Mellitus

PURPOSE

Real-time continuous glucose monitoring (RT-CGM) provides information on glycemic variability (GV), time in range (TIR), and guidance to avoid hypoglycemia, thereby complimenting HbA1c for diabetes management. We investigated whether GV and TIR were independently associated with chronic and acute diabetes complications.

METHODS

Between September 2014 and January 2017, 515 subjects with type 1 diabetes using sensor-augmented pump therapy were followed for 24 months. The link between baseline HbA1c and CGM-derived glucometrics (TIR [70-180 mg/dL], coefficient of variation [CV], and SD) obtained from the first 2 weeks of RT-CGM use and the presence of complications was investigated. Complications were defined as: composite microvascular complications (presence of neuropathy, retinopathy, or nephropathy), macrovascular complications, and hospitalization for hypoglycemia and/or ketoacidosis.

RESULTS

Individuals with microvascular complications were older (P < 0.001), had a longer diabetes duration (P < 0.001), a higher HbA1c (7.8 ± 0.9 vs 7.5 ± 0.9%, P < 0.001), and spent less time in range (60.4 ± 12.2 vs 63.9 ± 13.8%, P = 0.022) compared with those without microvascular complication. Diabetes duration (odds ratio [OR] = 1.12 [1.09-1.15], P < 0.001) and TIR (OR = 0.97 [0.95-0.99], P = 0.005) were independent risk factors for composite microvascular complications, whereas SD and CV were not. Age (OR = 1.08 [1.03-1.14], P = 0.003) and HbA1c (OR = 1.80 [1.02-3.14], P = 0.044) were risk factors for macrovascular complications. TIR (OR = 0.97 [0.95-0.99], P = 0.021) was the only independent risk factor for hospitalizations for hypoglycemia or ketoacidosis.

CONCLUSIONS

Lower TIR was associated with the presence of composite microvascular complications and with hospitalization for hypoglycemia or ketoacidosis. TIR, SD, and CV were not associated with macrovascular complications.

Glucose Variability: How Does It Work?

A growing body of evidence points to the role of glucose variability (GV) in the development of the microvascular and macrovascular complications of diabetes. In this review, we summarize data on GV-induced biochemical, cellular and molecular events involved in the pathogenesis of diabetic complications. Current data indicate that the deteriorating effect of GV on target organs can be realized through oxidative stress, glycation, chronic low-grade inflammation, endothelial dysfunction, platelet activation, impaired angiogenesis and renal fibrosis. The effects of GV on oxidative stress, inflammation, endothelial dysfunction and hypercoagulability could be aggravated by hypoglycemia, associated with high GV. Oscillating hyperglycemia contributes to beta cell dysfunction, which leads to a further increase in GV and completes the vicious circle. In cells, the GV-induced cytotoxic effect includes mitochondrial dysfunction, endoplasmic reticulum stress and disturbances in autophagic flux, which are accompanied by reduced viability, activation of apoptosis and abnormalities in cell proliferation. These effects are realized through the up- and down-regulation of a large number of genes and the activity of signaling pathways such as PI3K/Akt, NF-κB, MAPK (ERK), JNK and TGF-β/Smad. Epigenetic modifications mediate the postponed effects of glucose fluctuations. The multiple deteriorative effects of GV provide further support for considering it as a therapeutic target in diabetes.

Hypoglycaemia and Cardiovascular Disease Risk in Patients with Diabetes

Hypoglycaemia represents an important side effect of insulin therapy and insulin secretagogues. It can occur in both type 1 and type 2 diabetes mellitus patients. Also, some associations between hypoglycaemia and cardiovascular (CV) risk have been reported. Several mechanisms may be involved, including the sympathoadrenal system, hypokalaemia, endothelial dysfunction, coagulation, platelets, inflammation, atherothrombosis and impaired autonomic cardiac reflexes. This narrative review discusses the associations of hypoglycaemia with CV diseases, including coronary heart disease (CHD), cardiac arrhythmias, stroke, carotid disease and peripheral artery disease (PAD), as well as with dementia. Severe hypoglycaemia has been related to CHD, CV and all-cause mortality. Furthermore, there is evidence supporting an association between hypoglycaemia and cardiac arrhythmias, potentially predisposing to sudden death. The data linking hypoglycaemia with stroke, carotid disease and PAD is limited. Several factors may affect the hypoglycaemia-CV relationships, such as the definition of hypoglycaemia, patient characteristics, co-morbidities (including chronic kidney disease) and antidiabetic drug therapy. However, the association between hypoglycaemia and dementia is bilateral. Both the disorders are more common in the elderly; thus, glycaemic goals should be carefully selected in older patients. Further research is needed to elucidate the impact of hypoglycaemia on CV disease.

Cardiovascular disease in type 1 diabetes: A review of epidemiological data and underlying mechanisms

Cardiovascular disease (CVD) is highly prevalent in patients with type 1 diabetes (T1D) and a major cause of mortality. CVD arises earlier in life in T1D patients and is responsible for a significant reduction of at least 11 years' life expectancy. Also, the incidence of CVD is much more pronounced in patients with T1D onset at an earlier age. However, the factors responsible for increased atherosclerosis and CVD in T1D are not yet totally clarified. In addition to the usual cardiovascular (CV) risk factors, chronic hyperglycaemia plays an important role by promoting oxidative stress, vascular inflammation, monocyte adhesion, arterial wall thickening and endothelial dysfunction. Diabetic nephropathy and cardiac autonomic neuropathy are also associated with increased CVD in T1D. In fact, the CVD risk remains significantly increased even in well-controlled T1D patients who have no additional CV risk factors, indicating that other potential factors are likely to be involved. Hypoglycemia and glucose variability could enhance CV disease by promoting oxidative stress, vascular inflammation and endothelial dysfunction. Furthermore, even well-controlled T1D patients show significant qualitative and functional abnormalities of lipoproteins that are likely to be implicated in the development of atherosclerosis and premature CVD. In addition, recent data suggest that a dysfunctional immune system, which is typical of autoimmune T1D, might also promote CVD possibly through inflammatory pathways. Moreover, overweight and obese T1D patients can manifest additional CV risk through pathophysiological mechanisms resembling those observed in type 2 diabetes (T2D).

Vascular Complication in Adolescents With Diabetes Mellitus

Diabetes mellitus is becoming more prevalent and even with new advancements which improve glycaemic control, complications of diabetes are common. Vascular complications of diabetes include the microvascular complications: retinopathy, nephropathy, and peripheral and autonomic neuropathy. Macrovascular complications are also common in patients with diabetes and arguably more concerning as they confer a high mortality risk yet are sometimes under-treated. Risk factors for diabetes complications start to occur in childhood and adolescents and some youths may be diagnosed with complications before transition to adult care. This article discusses the prevalence, risk factors, screening, and treatment recommendations for vascular complications in children and adolescents with diabetes.

Early Endothelial Dysfunction in Type 1 Diabetes Is Accompanied by an Impairment of Vascular Smooth Muscle Function: A Meta-Analysis

Background: A large yet heterogeneous body of literature exists suggesting that endothelial dysfunction appears early in type 1 diabetes, due to hyperglycemia-induced oxidative stress. The latter may also affect vascular smooth muscles (VSM) function, a layer albeit less frequently considered in that pathology. This meta-analysis aims at evaluating the extent, and the contributing risk factors, of early endothelial dysfunction, and of the possible concomitant VSM dysfunction, in type 1 diabetes. Methods: PubMed, Web of Sciences, Cochrane Library databases were screened from their respective inceptions until October 2019. We included studies comparing vasodilatory capacity depending or not on endothelium (i.e., endothelial function or VSM function, respectively) in patients with uncomplicated type 1 diabetes and healthy controls. Results: Fifty-eight articles studying endothelium-dependent function, among which 21 studies also assessed VSM, were included. Global analyses revealed an impairment of standardized mean difference (SMD) (Cohen's d) of endothelial function: -0.61 (95% CI: -0.79, -0.44) but also of VSM SMD: -0.32 (95% CI: -0.57, -0.07). The type of stimuli used (i.e., exercise, occlusion-reperfusion, pharmacological substances, heat) did not influence the impairment of the vasodilatory capacity. Endothelial dysfunction appeared more pronounced within macrovascular than microvascular beds. The latter was particularly altered in cases of poor glycemic control [HbA_1c > 67 mmol/mol (8.3%)]. Conclusions: This meta-analysis not only corroborates the presence of an early impairment of endothelial function, even in response to physiological stimuli like exercise, but also highlights a VSM dysfunction in children and adults with type 1 diabetes. Endothelial dysfunction seems to be more pronounced in large than small vessels, fostering the debate on their relative temporal appearance.

Endothelial Dysfunction is Related to Glycemic Variability and Quality and Duration of Sleep in Adults With Type 1 Diabetes

BACKGROUND

Elevated cardiovascular disease risk in people with type 1 diabetes (T1DM) is incompletely understood. Glycemic control, glycemic variability, and sleep quality and duration may relate to cardiovascular disease risk in this population via endothelial dysfunction.

OBJECTIVE

The aim of this study was to examine relationships among glycemic control, glycemic variability, sleep quality and duration, and endothelial function in adults with T1DM.

METHODS

Endothelial function was measured using flow-mediated dilation. Glycemic control and glycemic variability were measured using A1C and a continuous glucose monitor, respectively; sleep quality and duration were measured with the Pittsburgh Sleep Quality Index.

RESULTS

Twenty subjects were recruited. Reduced flow-mediated dilation and higher glucose levels were associated with poorer sleep quality (r = -0.51, P = .01; r = 0.52, P = .03). Subjects with shorter sleep duration had greater glycemic variability.

CONCLUSIONS

Endothelial dysfunction (a precursor to cardiovascular disease) relates to glycemic control, glycemic variability, and sleep quality in T1DM.

Relationship between glucose control, glycemic variability, and oxidative stress in children with type 1 diabetes

INTRODUCTION

Few studies assessing the relationship between oxidative stress and glycemic variability in children with type 1 diabetes mellitus (T1DM) are available, and most of them reported no significant results.

OBJECTIVE

To assess the relationship between glucose control, glycemic variability, and oxidative stress as measured by urinary excretion of 8-iso-prostanglandin F2-alpha (8-iso-PGF2α) in children with T1DM.

MATERIALS AND METHODS

A cross-sectional study including 25 children with T1DM. Participants were evaluated during five days in two different situations: 1st phase during a summer camp, and 2nd phase in their everyday life at home. The following data were collected in each study phase:. - Six capillary blood glucose measurements per day. Mean blood glucose (MBG) levels and glucose variability parameters, including standard deviation, coefficient of variation, and mean amplitude of glycemic excursions (MAGE), were calculated. - Capillary HbA1c level. - 24-h urine sample to measure 8-iso-PGF2α.

RESULTS

There were no statistically significant differences in urinary 8-iso-PGF2α levels (142±37 vs. 172±61pg/mg creatinine) and glucose control and glycemic variability parameters between both phases. In the 2nd phase, statistically significant correlations were found between urinary 8-iso-PGF2α and HbA1c levels (r=0.53), MBG (r=0.72), standard deviation (r=0.49), and MAGE (r=0.42). No significant correlations between glucose control, glycemic variability and urinary 8-iso-PGF2α excretion were found in the 1st phase.

CONCLUSIONS

A significant correlation was found between glycemic variability and HbA1c level and urinary 8-iso-PGF2α excretion in a group of children with T1DM during their daily lives. Additional studies are needed to confirm this finding and to explore its long-term impact on health.

Hypoglycemia does not affect the progression of preclinical atherosclerosis in subjects with type 2 diabetes

Introduction

Intensive treatment aimed at achieving optimal metabolic control to prevent the development of chronic diabetic complications is often associated with an increased rate of hypoglycemic events. Hypoglycemia is believed to be responsible for acute fatal and nonfatal cardiovascular events likely as a consequence of the activation of pro-inflammatory and pro-atherothrombotic pathways. Hypoglycemia has been reported to influence the development of preclinical atherosclerosis. The present study was designed to prospectively evaluate whether hypoglycemia influences the function and the morphology of the arteries in subjects with type 2 diabetes without complications and uncontrolled diabetes.

Material and methods

Seventy-six subjects underwent a noninvasive evaluation of carotid wall thickness and brachial artery function at baseline and after one year of treatment with the intent of obtaining optimal glycemic control. At the end of the observation time, subjects were divided in two groups: with hypoglycemia (H-group) or without hypoglycemia (C-group).

Results

Baseline characteristic were comparable between groups. HbA1c significantly decreased in both groups, and fasting plasma glucose was only significant in the H-group. Subjects with hypoglycemia showed a significant reduction of carotid wall thickness after one-year of treatment (H-groups: right baseline 834±141 vs. 1-year 770±132 μ p<0.05; C-group: 757±162 vs. 767±135 μ p = ns). Endothelial function remained unchanged during the study for both groups.

Discussion

The present findings demonstrate that hypoglycemia does not affect endothelial function. Furthermore, subjects who experience more hypoglycemia show significant reduction of carotid wall thickness. Optimal metabolic control should be pursued as soon as possible.

Nanotechnology in cell replacement therapies for type 1 diabetes

Islet transplantation is a promising long-term, compliance-free, complication-preventing treatment for type 1 diabetes. However, islet transplantation is currently limited to a narrow set of patients due to the shortage of donor islets and side effects from immunosuppression. Encapsulating cells in an immunoisolating membrane can allow for their transplantation without the need for immunosuppression. Alternatively, "open" systems may improve islet health and function by allowing vascular ingrowth at clinically attractive sites. Many processes that enable graft success in both approaches occur at the nanoscale level-in this review we thus consider nanotechnology in cell replacement therapies for type 1 diabetes. A variety of biomaterial-based strategies at the nanometer range have emerged to promote immune-isolation or modulation, proangiogenic, or insulinotropic effects. Additionally, coating islets with nano-thin polymer films has burgeoned as an islet protection modality. Materials approaches that utilize nanoscale features manipulate biology at the molecular scale, offering unique solutions to the enduring challenges of islet transplantation.

Management of diabetes complications in youth

Type 1 and type 2 diabetes are increasing in prevalence and diabetes complications are common. Diabetes complications are rarely studied in youth, despite the potential onset in childhood. Microvascular complications of diabetes include retinopathy, diabetic kidney disease or nephropathy, and neuropathy that may be somatic or autonomic. Macrovascular disease is the leading cause of death in patients with type 1 diabetes. Strict glycaemic control will reduce microvascular and macrovascular complications; however, they may still manifest in youth. This article discusses the diagnosis and treatment of complications that arise from type 1 and type 2 diabetes mellitus in youth. Screening for complications is paramount as early intervention improves outcome. Screening should commence from 11 years of age depending on the duration of type 1 diabetes or at diagnosis for patients with type 2 diabetes. Diabetic retinopathy may require invasive treatment such as laser therapy or intravitreal antivascular endothelial growth factor therapy to prevent future blindness. Hypertension and albuminuria may herald diabetic nephropathy and require management with angiotensin converting enzyme (ACE) inhibition. In addition to hypertension, dyslipidaemia must be treated to reduce macrovascular complications. Interventional trials aimed at examining the treatment of diabetes complications in youth are few. Statins, ACE inhibitors and metformin have been successfully trialled in adolescents with type 1 diabetes with positive effects on lipid profile, microalbuminuria and measures of vascular health. Although relatively rare, complications do occur in youth and further research into effective treatment for diabetes complications, particularly therapeutics in children in addition to prevention strategies is required.

Mitochondrial regulation of diabetic vascular disease: an emerging opportunity

Diabetes-related vascular complication rates remain unacceptably high despite guideline-based medical therapies that are significantly more effective in individuals without diabetes. This critical gap represents an opportunity for researchers and clinicians to collaborate on targeting mechanisms and pathways that specifically contribute to vascular pathology in patients with diabetes mellitus. Dysfunctional mitochondria producing excessive mitochondrial reactive oxygen species (mtROS) play a proximal cell-signaling role in the development of vascular endothelial dysfunction in the setting of diabetes. Targeting the mechanisms of production of mtROS or mtROS themselves represents an attractive method to reduce the prevalence and severity of diabetic vascular disease. This review focuses on the role of mitochondria in the development of diabetic vascular disease and current developments in methods to improve mitochondrial health to improve vascular outcomes in patients with DM.

Glucose Variability and Coronary Artery Disease

Fasting blood glucose, postprandial blood glucose and glycated haemoglobin are considered three important indicators for diabetes treatment. There is increasing evidence that glucose variability has more detrimental effects on the coronary arteries than does chronic sustained hyperglycaemia. This overview summarises recent findings in the field of glucose variability and its possible relationship with coronary artery disease. Glucose variability may be a marker of increased progression of coronary disease and plaque vulnerability. It might be a potential new therapeutic target for secondary prevention of coronary artery disease. Future studies will focus on the early detection and control of glucose variability to improve the clinical outcomes in patients with coronary artery disease.

Macrovascular disease and risk factors in youth with type 1 diabetes: time to be more attentive to treatment?

Cardiovascular disease remains the leading cause of mortality in patients with type 1 diabetes. Although cardiovascular disease complications are rare until adulthood, pathology and early markers can manifest in adolescence. Whereas advances have been made in the management of microvascular complications of type 1 diabetes, similar progress in reducing macrovascular complications has not been made. The reasons for the absence of progress remain incompletely understood, but most likely relate to the long time needed for cardiovascular disease to manifest clinically and hence for risk factor management to show a clinical benefit, thus allowing inertia to prevail for diagnosis and particularly for targeting risk factors. In this Review, we summarise paediatric data on traditional and novel risk factors of cardiovascular disease, provide an overview of data from previous and current clinical trials, discuss future directions in cardiovascular disease research for paediatric patients with type 1 diabetes, and advocate for the early identification and treatment of cardiovascular disease risk factors as recommended in multiple guidelines.

Hemoglobin A1c predicts hemorrhagic transformation and poor outcomes after acute anterior stroke

BACKGROUND AND PURPOSE

Hemorrhagic transformation (HT) is a major complication of acute ischaemic stroke that is potentially related to clinical deterioration. The objective of this study was to assess whether chronic hyperglycemia is a predictive factor of HT in patients with acute anterior stroke.

METHODS

Patients with acute anterior stroke were included in this study. Hemoglobin A1c (HbA1c) was measured in the morning after hospitalization. HT was detected by computed tomography scans or gradient echo magnetic resonance imaging performed 4 (±2) days after onset. Univariate and multivariate logistic regression analyses were used to assess the risks for HT and short-term outcomes.

RESULTS

Of the 426 patients included, 93 (21.8%) had HT: 61 (14.3%) presented with hemorrhagic infarction and 32 (7.5%) presented with parenchymal hematoma. A total of 54 patients received thrombolytic treatment and 18 (33.3%) were found to have HT. In the multivariate analysis, HbA1c [odds ratio (OR), 1.294; 95% confidence interval (CI), 1.097-1.528], infarction size (OR, 3.358; 95% CI, 1.748-6.449) and thrombolytic therapy (OR, 3.469; 95% CI, 1.757-6.847) were predictors of HT. The predictive effect of HbA1c on HT was still observed in both groups when patients were stratified according to the levels of fasting blood glucose. HbA1c was found to be a predictor of poor outcomes in the multilogistic regression analysis (OR, 1.482; 95% CI, 1.228-1.788).

CONCLUSIONS

Higher HbA1c was independently related to HT and poor neurological outcomes in patients with ischaemic stroke. These findings have significant implications for the treatment of diabetes and glucose management in patients with diabetes mellitus and/or acute ischaemic stroke.

Relationship of Hyperglycaemia, Hypoglycaemia, and Glucose Variability to Atherosclerotic Disease in Type 2 Diabetes

OBJECTIVE

Type 2 diabetes mellitus (T2DM) is known to be associated with increased cardiovascular risk. The aim of this study was therefore to investigate the independent effects of hyperglycaemia, hypoglycaemia, and glucose variability on microvascular and macrovascular disease in T2DM.

METHODS

Subjects with T2DM of <10 years duration and on stable antiglycaemic treatment underwent carotid intima-media thickness (CIMT), ankle-brachial index (ABI), albumin-creatinine ratio (ACR), and HbA_1c measurement, as well as 72-hour continuous glucose monitoring. Macrovascular disease was defined as one or more of the following: history of ischaemic heart disease (IHD), cerebrovascular accident (CVA), ABI < 0.9, or abnormal CIMT.

RESULTS

The study population comprised 121 subjects with T2DM (89 males : 32 females). The mean age was 62.6 years, and the mean DM duration was 3.7 years. Macrovascular disease was present in 71 patients (58.7%). In multivariate logistic regression analysis, body surface area (BSA) (OR 18.88 (95% CI 2.20-156.69), p = 0.006) and duration of blood glucose (BG) < 3.9 mmol/L (OR 1.12 (95% CI 1.014-1.228), p = 0.024) were independent predictors of macrovascular disease. BSA (OR 12.6 (95% CI 1.70-93.54), p = 0.013) and duration of BG < 3.9 mmol/L (OR 1.09 (95% CI 1.003-1.187), p = 0.041) were independent predictors of abnormal CIMT. Area under the curve for BG > 7.8 mmol/L (β = 15.83, p = 0.005) was the sole independent predictor of albuminuria in generalised linear regression.

CONCLUSIONS

This study demonstrates that hypoglycaemia is associated with the occurrence of atherosclerotic disease while hyperglycaemia is associated with microvascular disease in a Caucasian population with T2DM of recent duration.

The potential effect of ultra-long insulin degludec on glycemic variability

Despite the therapeutic advances in the treatment of diabetes, metabolic control instability due to glycemic variability (GV) is frequently observed in patients with diabetes on intensive insulin therapy and is associated with hyperglycemic peaks and hypoglycemic episodes. Hyperglycemia associated with GV has been implicated in the development of chronic complications due to its pro-oxidative consequences. On the other hand, hypoglycemia can be associated with increased cardiovascular risk secondarily to adrenergic activation. The ultra-long-acting insulin analogue, insulin degludec (IDeg), presents a flat and stable glucose-lowering effect both in Type 1 and Type 2 diabetes patients. In pharmacodynamic studies, IDeg has been associated with a lower variability in its insulin action than other alternatives for basal insulin, which might have clinical advantages for the stability of the glycemic control. The main objective of this review is to present pharmacological and clinical data regarding the efficacy and safety of IDeg for the treatment of diabetes focusing on its effects on GV and on hypoglycemia frequency.

Higher-Than-Conventional Subcutaneous Regular Insulin Doses Following Diabetic Ketoacidosis in Children and Adolescents

OBJECTIVE

To evaluate the effect of initial insulin dosage on glycemic control in the first 48 hours of subcutaneous regular insulin therapy after resolution of diabetic ketoacidosis (DKA).

METHODS

Records of patients with DKA hospitalized in the past 3 years [n=76, median age=10.0 (6.0-12.0) years, Male/Female: 44/32] were reviewed. The patients were designated into two groups according to distribution of starting doses of subcutaneous insulin. Group 1 (n=28) received a median dose of 1.45 U/kg/day (1.41-1.5) and group 2 (n=48) a median dose of 0.96 U/kg/day (0.89-1). Clinical and laboratory data were analyzed.

RESULTS

Median, minimum, and maximum blood glucose levels of Group 1 in the first 48 hours of treatment were significantly lower than that of Group 2 [213 (171-242) vs. 255 (222-316), p=<0.001; 102 (85-151) vs. 129 (105-199), p=0.004; and 335 (290-365) vs. 375 (341-438), p=0.001, respectively]. The number of patients who experienced hypoglycemia (<70 mg/dL) were similar [Group 1, 5 (17.9%) vs. Group 2, 4 (8.3%), p=0.276] and none had severe hypoglycemia. In Group 1, the ratio of blood glucose levels within the target range (100-200 mg/dL) were higher (37.5% vs. 12.5%) and the number of results >200 mg/dL were lower (50% vs. 81.3%) compared to Group 2 (p=0.001 and p<0.001, respectively).

CONCLUSION

After resolution of DKA, a higher initial dose of 1.4-1.5 U/kg/day regular insulin is associated with better glycemic control in children and adolescents without an increase in risk of hypoglycemia.

Influence of initial insulin dosage on blood glucose dynamics of children and adolescents with newly diagnosed type 1 diabetes mellitus

OBJECTIVE

To investigate the effect of initial insulin dosage on blood glucose (BG) dynamics, β-cell protection, and oxidative stress in type 1 diabetes mellitus.

METHODS

Sixty newly diagnosed type 1 diabetes mellitus patients were randomly assigned to continuous subcutaneous insulin infusions of 0.6 ± 0.2 IU/kg/d (group 1), 1.0 ± 0.2 IU/kg/d (group 2), or 1.4 ± 0.2 IU/kg/d (group 3) for 3 wk. BG was monitored continuously for the first 10 d and the last 2 d of wk 2 and 3. A total of 24-hour urinary 8-iso-PGF2α was assayed on days 8, 9, and 10. The occurrence and duration of the honeymoon period were recorded. Fasting C-peptide and glycosylated hemoglobin (HbA1c) were assayed after 1, 6, and 12 months of insulin treatment.

RESULTS

BG decreased to the target range by the end of wk 3 (group 1), wk 2 (group 2), or wk 1 (group 3). The actual insulin dosage over the 3 wk, frequency of hypoglycemia on wk 1 and 2, and median BG at the end of wk 1 differed significantly, but not 8-iso-PGF2α and the honeymoon period in the three groups. No severe hypoglycemia event was observed in any patient, but there was significant difference in the first occurrence of hypoglycemia.

CONCLUSIONS

Differences in initial insulin dosage produced different BG dynamics in wk 1, equivalent BG dynamics on wk 2 and 3, but had no influence on short- and long-term BG control and honeymoon phase. The wide range of initial insulin dosage could be chosen if guided by BG monitoring.

Study of Glycemic Variability Through Time Series Analyses (Detrended Fluctuation Analysis and Poincaré Plot) in Children and Adolescents with Type 1 Diabetes

BACKGROUND

Time series analysis provides information on blood glucose dynamics that is unattainable with conventional glycemic variability (GV) indices. To date, no studies have been published on these parameters in pediatric patients with type 1 diabetes. Our aim is to evaluate the relationship between time series analysis and conventional GV indices, and glycosylated hemoglobin (HbA1c) levels.

METHODS

This is a transversal study of 41 children and adolescents with type 1 diabetes. Glucose monitoring was carried out continuously for 72 h to study the following GV indices: standard deviation (SD) of glucose levels (mg/dL), coefficient of variation (%), interquartile range (IQR; mg/dL), mean amplitude of the largest glycemic excursions (MAGE), and continuous overlapping net glycemic action (CONGA). The time series analysis was conducted by means of detrended fluctuation analysis (DFA) and Poincaré plot.

RESULTS

Time series parameters (DFA alpha coefficient and elements of the ellipse of the Poincaré plot) correlated well with the more conventional GV indices. Patients were grouped according to the terciles of these indices, to the terciles of eccentricity (1: 12.56-16.98, 2: 16.99-21.91, 3: 21.92-41.03), and to the value of the DFA alpha coefficient (> or ≤1.5). No differences were observed in the HbA1c of patients grouped by GV index criteria; however, significant differences were found in patients grouped by alpha coefficient and eccentricity, not only in terms of HbA1c, but also in SD glucose, IQR, and CONGA index.

CONCLUSIONS

The loss of complexity in glycemic homeostasis is accompanied by an increase in variability.

Glucose variability, HbA1c and microvascular complications

Microvascular complications in diabetes are associated with poor long-term diabetes control as measured by HbA1c levels. Glucose fluctuations are related to oxidative stress, endothelial dysfunction, and inflammation, factors traditionally associated with the pathogenesis of vascular damage. Glucose variability has been associated with macrovascular disease in some studies but any association with microvascular disease remains controversial. This overview summarizes recent findings in the field of glucose variability and its possible relationship with retinopathy, nephropathy and neuropathy. It is concluded that randomized prospective follow-up trials could possibly help estimate whether short-term glucose variability should be considered as an independent risk factor for microvascular complications in diabetes.

Impact of Real-Time Continuous Glucose Monitoring Use on Glucose Variability and Endothelial Function in Adolescents with Type 1 Diabetes: New Technology--New Possibility to Decrease Cardiovascular Risk?

Children with type 1 diabetes (T1DM) are the high-risk group of accelerated atherosclerosis. Real-time continuous glucose monitoring (RT-CGM) provides possibilities for the detection of glycaemic variability, newly recognized cardiovascular risk factor. The aim of the study was to assess the usefulness of RT-CGM as an educational tool to find and reduce glycaemic variability in order to improve endothelial function in T1DM adolescents. Forty patients aged 14.6 years were recruited. The study was based on one-month CGM sensors use. Parameters of glycaemic variability were analyzed during first and last sensor use, together with brachial artery flow-mediated dilatation (FMD) to assess endothelial function. In the whole group, FMD improvement was found (10.9% to 16.6%, p < 0.005), together with decrease in all studied glycaemic variability parameters. In patients with HbA1c improvement compared to the group without HbA1c improvement, we found greater increase of FMD (12% to 19%, p < 0.005 versus 8.2% to 11.3%, p = 0.080) and greater improvement of glucose variability. RT-CGM can be considered as an additional tool that offers T1DM adolescents the quick reaction to decrease glycaemic variability in short time observation. Whether such approach might influence improvement in endothelial function and reduction of the risk of future cardiovascular disease remains to be elucidated.

Longitudinal evaluation of endothelial function in children and adolescents with type 1 diabetes mellitus: a long-term follow-up study

BACKGROUND

Type 1 diabetes (T1DM) predisposes to cardiovascular disease, increasing the risk to develop atherosclerosis. In the pediatric population, the cardiovascular risk may be evaluated examining endothelial function by a non-invasive ultrasound technique, namely flow-mediated dilation (FMD) of the brachial artery. The aims of this study were the longitudinal evaluation of the potential change in the endothelium-dependent vasomotor function in children and adolescents with T1DM and the identification of clinical and laboratory data correlated to modifications.

METHODS

We studied 39 T1DM patients (20 girls and 19 boys; aged 11.2 ± 3.72 years). FMD and blood samples were obtained from all patients at baseline (time 0) and after a follow up of at least 1 year (time 1). FMD was also evaluated in 45 healthy controls (22 boys, 23 girls) aged 10.2 ± 3.05 years.

RESULTS

At time 0, 43.6% of T1DM patients presented an impaired FMD. FMD at time 1 revealed a dramatic impairment of endothelial function: altered FMD values were shown in 61.5% of patients and it got worse in 74.3% of them. Longitudinally, boys had a greater impairment of FMD than girls. At baseline, multivariate analysis identified only sex as significant predictor of FMD (β = 0.470, P = 0.029).

CONCLUSIONS

Because endothelial dysfunction appears earlier in diabetic children, they are at higher risk to develop atherosclerosis. Our results suggest the usefulness of FMD as a tool to stratify pediatric T1DM patients according to their cardiovascular risk and to follow them up longitudinally.

Detection and treatment efficacy of hypoglycemic events in the everyday life of children younger than 7 yr

BACKGROUND

Mild hypoglycemia is commonly observed in children treated for type 1 diabetes mellitus (T1DM). Hypoglycemia disturbs cognition and learning.

OBJECTIVE

To describe how and to what extent hypoglycemia in young children with T1DM is detected in everyday life. To learn how parents and caregivers treat hypoglycemia and to evaluate how efficient this treatment is.

METHODS

Twenty-three children [12 girls, mean age: 4.5 yr, mean HbA1c: 59 mmol/mol (7.5%)], 17 of whom were treated with an insulin pump, underwent blinded continuous glucose monitoring (CGM). Data on symptoms and treatment of hypoglycemia were collected in a logbook. Plasma glucose values were collected through self-monitoring of blood glucose and entered in the logbook, and glucometer memories were uploaded. Data were collected during 1 wk in autumn and 1 wk in spring.

RESULTS

Only 32% of all hypoglycemic events were detected despite plasma glucose being checked 10 times per day. Most hypoglycemic events were asymptomatic (90% overall and 98% of those occurring at night). Untreated hypoglycemic events were associated with a relapse into hypoglycemia within 3 h in the majority of events. Compared to treatment of hypoglycemia events with a defined dose of simple carbohydrates, treatment with a mixed meal resulted in a significantly higher glucose value 1 and 2 h after the hypoglycemia.

CONCLUSION

For optimum treatment, children younger than 7 yr with T1DM need better strategies and support for detecting hypoglycemia with real-time CGM. Hypoglycemia should be treated with a defined dose of carbohydrates rather than a mixed meal.

Detection of vascular risk markers in children and adolescents with type 1 diabetes

OBJECTIVES

Type 1 diabetes is a chronic disease that causes persistent vascular injury. This study investigates the benefits of surrogate markers in early detection of vascular injury in children and adolescents with type 1 diabetes.

METHODS

Eighty-four patients (35 male, 49 female) with type 1 diabetes for 5 or more years were included. Serum lipid profile, plasminogen activator inhibitor-1 (PAI-1), lipoprotein (a) (Lpa) and homocystein, were investigated. Patients were divided into two groups according to the duration of diabetes. Patients with and without microvascular complications were also compared.

RESULTS

Microvascular complications were present in 14 out of 48 patients in group-1 (29.1%; duration of diabetes: 5-10 years) and in 7 out of 36 patients in group-2 (19.4%; duration of diabetes: >10 years). Serum homocystein, Lpa, PAI-1 and serum lipids were not correlated with the duration of diabetes. Significantly increased triglyceride (TG) and HbA1C levels were associated with the presence of microvascular complications.

CONCLUSION

Providing good glycemic control is very important for preventing vascular injury in children and adolescents with type 1 diabetes. It seems that traditional vascular surrogate markers like LDL/HDL ratio, triglycerides and HbA1C level correspond more to microvascular complications than newly defined surrogate markers that are not commonly available.

Effects of glucose control and variability on endothelial function and repair in adolescents with type 1 diabetes

Background. Endothelial dysfunction and increased inflammation are precursors of cardiovascular disease in type 1 diabetes (T1D) and occur even in adolescents with T1D. The goal of this study was to determine the relationship of endothelial dysfunction to various measures of glycemia. Research Design and Methods. Forearm blood flow (FBF, venous occlusion plethysmography) was measured before and after 5 min of upper arm vascular occlusion in 17 adolescents with uncomplicated type 1 diabetes. Endothelial function was assessed as postocclusion FBF and forearm vascular resistance (FVR, mean arterial pressure/FBF). Fasting glucose, 72 hour mean glucose and standard deviation from continuous glucose monitoring, hemoglobin A1c, and hemoglobin A1c by duration area under the curve were used to assess immediate, short-term, and intermediate- and long-term glycemia. Results. Postocclusion FBF (r = −0.53, P = 0.030) negatively correlated and postocclusion FVR positively correlated (r = 0.52, P = 0.031) with hemoglobin A1c levels. FVR was positively associated with log 3 day mean glucose (r = 0.55, P = 0.027). Postocclusion FBF (2.8 ± 1.1 versus 3.4 ± 0.5 mL/dL/min, mean ± SE, P = 0.084) tended to be lower and FVR (31.4 ± 10.4 versus 23.9 ± 4.4 mmHg dL min/mL, P = 0.015) was significantly higher in subjects with hemoglobin A1c above the median (8.3%) compared to those with lower hemoglobin A1c levels. Conclusions. These results demonstrate that poor intermediate-term glycemic control is associated with impaired endothelial function.

[Glycemic variability and oxidative stress in children, with type 1 diabetes attending a summer camp]

OBJECTIVE

To assess glycemic variability, oxidative stress and their relationship in children and adolescents with type 1 diabetes (T1DM) attending a summer camp.

PATIENTS AND METHOD

Cross-sectional study that included 54 children and adolescents with T1DM aged 7-16, attending a 7 day summer camp. Sociodemographic information, clinical data, and blood glucose values measured using an Accu-Chek Nano® glucose meter were recorded. Glucose variability markers (standard deviation [SD], low blood glucose index [LBGI], high blood glucose index [HBGI], mean amplitude of glycemic excursions [MAGE] and mean of daily differences [MODD]) were calculated. Oxidative stress was assessed by the measurement of 8-iso-prostaglandin F2 alpha (PGF2α) in a 24-hour urine sample collected at the end of the camp in 14 children.

RESULTS

The Median SD, MAGE and MODD indexes were in the high range (61, 131 and 58 mg/dl, respectively), LBGI in the moderate range (3.3), and HBGI in the low range (4.5). The mean HbA1c was 7.6% and the median urinary excretion rate of 8-iso-PGF2α was 864.39 pg/mg creatinine. The Spearman correlation coefficients between markers of glycemic variability (SD, HBGI, MAGE, MODD) were significant. Non-significant correlations were found between markers of glycemic variability and urinary 8-iso-PGF2α.

CONCLUSIONS

High glycemic variability was observed in children and adolescents attending a summer camp. However, no correlations were found between markers of glycemic variability and oxidative stress measured by urinary 8-iso-PGF2α. Further studies are needed to address the relationship between oxidative stress and glycemic variability in children with T1DM.

Vascular function and glucose variability improve transiently following initiation of continuous subcutaneous insulin infusion in children with type 1 diabetes

OBJECTIVE

The effect of continuous subcutaneous insulin infusion (CSII) and glucose variability on vascular health in type 1 diabetes (T1D) is not known. We aimed to determine whether initiation of CSII improves vascular function and reduces glucose variability, independent of changes in HbA1c.

METHODS

Twenty-two children with T1D (12.5 ± 2.9 yr) were reviewed immediately prior, 3 wk, and 12 months after initiation of CSII. Vascular function [flow-mediated dilatation (FMD), glyceryl trinitrate-mediated dilatation (GTN)], glucose variability [mean of daily differences (MODD), mean amplitude of glycaemic excursions (MAGE) and continuous overlapping net glycaemic action (CONGA)], and clinical and biochemical data were measured at each visit. Results for the first two visits were compared to a previously studied cohort of 31 children with T1D who remained on multiple daily injections (MDI).

RESULTS

FMD, GTN, blood pressure, HbA1c, fructosamine, and glucose variability significantly improved 3 wk after CSII commencement (all p < 0.05), but there was no change in the MDI control group. At 3 wk, vascular function related to glucose variability [(FMD: MODD, r = -0.62, p = 0.002) and (GTN: MAGE, r = -0.59, p = 0.004; CONGA-4, r = -0.51, p = 0.01; MODD, r = -0.62, p = 0.002)] but not to blood pressure, HbA1c, or fructosamine. At 12 months, FMD, GTN, blood pressure, and glucose variability returned to baseline levels, while HbA1c deteriorated. Carotid intima media thickness was unchanged over 12 months.

CONCLUSIONS

Initiation of CSII rapidly improves vascular function in association with decreased glucose variability; however, the effects are not sustained with deterioration of metabolic control and glucose variability.

Relationship between fluctuations in glucose levels measured by continuous glucose monitoring and vascular endothelial dysfunction in type 2 diabetes mellitus

Background

Fluctuations in blood glucose level cause endothelial dysfunction and play a critical role in onset and/or progression of atherosclerosis. We hypothesized that fluctuation in blood glucose levels correlate with vascular endothelial dysfunction and that this relationship can be assessed using common bedside medical devices.

Methods

Fluctuations in blood glucose levels were measured over 24 hours by continuous glucose monitoring (CGM) on admission day 2 in 57 patients with type 2 diabetes mellitus. The reactive hyperemia index (RHI), an index of vascular endothelial function, was measured using peripheral arterial tonometry (EndoPAT) on admission day 3.

Results

The natural logarithmic-scaled RHI (L_RHI) correlated with SD (r=−0.504; P<0.001), the mean amplitude of glycemic excursions (MAGE) (r=−0.571; P<0.001), mean postprandial glucose excursion (MPPGE) (r=−0.411; P=0.001) and percentage of time ≥200 mg/dl (r=−0.292; P=0.028). In 12 patients with hypoglycemia, L_RHI also correlated with the percentage of time at hypoglycemia (r=−0.589; P=0.044). L_RHI did not correlate with HbA1c or fasting plasma glucose levels. Furthermore, L_RHI did not correlate with LDL cholesterol, HDL cholesterol, and triglyceride levels or with systolic and diastolic blood pressures. Finally, multivariate analysis identified MAGE as the only significant determinant of L_RHI.

Conclusions

Fluctuations in blood glucose levels play a significant role in vascular endothelial dysfunction in type 2 diabetes.

Trial registration

UMIN000007581

Continuous glucose monitoring after islet transplantation in type 1 diabetes: an excellent graft function (β-score greater than 7) Is required to abrogate hyperglycemia, whereas a minimal function is necessary to suppress severe hypoglycemia (β-score greater than 3)

CONTEXT

For the last 10 yr, continuous glucose monitoring (CGM) has brought up new insights into the accuracy of blood glucose analysis.

OBJECTIVE

Our objective was to determine how islet graft function was able to influence the various components of dysglycemia after islet transplantation (IT).

DESIGN AND SETTING

We conducted a single-arm open-labeled study with a 3-yr follow-up in a referral center (ClinicalTrial.gov identifiers NCT00446264 and NCT01123187).

PATIENTS

Twenty-three consecutive patients with type 1 diabetes (14 islet alone, nine islet after kidney) received IT within 3 months using the Edmonton protocol.

INTERVENTION

INTERVENTION included 72-h CGM before and 3, 6, 9, 12, 24, and 36 months after transplantation.

MAIN OUTCOME MEASURE

Graft function was estimated via β-score, a previously validated index (range 0-8) based on treatment requirements, C-peptide, blood glucose, and glycated hemoglobin.

RESULTS

At the 3-yr visit, graft function persisted in 19 patients (82%), and 10 (43%) remained insulin independent. Glycated hemoglobin decreased in the whole cohort from 8.3% (7.3-9.0%) at baseline to 6.7% (5.9-7.7%) at 3 yr [median (interquartile range), P < 0.01]. Mean glucose, glucose sd, and time spent with glycemia above 10 mmol/liter (hyperglycemia) and below 3 mmol/liter (hypoglycemia) were significantly lower after IT (P < 0.05 vs. baseline). The four CGM outcomes were related to β-score (P < 0.001). However, partial function (β-score >3) was sufficient to abrogate hypoglycemia; suboptimal function (β-score >5) was necessary to significantly improve mean glucose, glucose sd, and hyperglycemia; and optimal function (β score >7) was necessary to normalize them.

CONCLUSION

The four components of dysglycemia were not equally affected by the degree of islet graft function, which could have important implications for future development of β-cell replacement. A β-score above 3 dramatically reduced the occurrence of hypoglycemia.