OGTT is recommended for glucose homeostasis assessments in Friedreich ataxia

Insulin sensitivity and insulin secretion in adults with Friedreich's Ataxia: the role of skeletal muscle

INTRODUCTION

Friedreich's Ataxia (FRDA) is a multi-system disorder caused by frataxin deficiency. FRDA-related diabetes mellitus (DM) is common. Frataxin supports skeletal muscle mitochondrial oxidative phosphorylation (OXPHOS) capacity, a mediator of insulin sensitivity. Our objective was to test the association between skeletal muscle health and insulin sensitivity and secretion in adults with FRDA without DM.

METHODS

Case-control study (NCT02920671). Glucose and insulin metabolism (stable-isotope oral glucose tolerance tests), body composition (dual-energy x-ray absorptiometry), physical activity (self-report), and skeletal muscle OXPHOS capacity (creatine chemical exchange saturation transfer MRI) were assessed.

RESULTS

Participants included 11 individuals with FRDA (4 female), median age 27y (IQR 23, 39), BMI 26.9kg/m2 (24.1, 29.4), and 24 controls (11 female), 29y (26, 39), 24.4kg/m2 (21.8, 27.0). Fasting glucose was higher in FRDA (91 vs. 83mg/dL (5.0 vs. 4.6mmol/L), p<0.05). Individuals with FRDA had lower insulin sensitivity (WBISI 2.8 vs. 5.3, p<0.01), higher post-prandial insulin secretion (insulin secretory rate iAUC 30-180 minutes, 24,652 vs. 17,858, p<0.05), and more suppressed post-prandial endogenous glucose production (-0.9% vs. 26.9% of fasting EGP, p<0.05). In regression analyses, lower OXPHOS and inactivity explained some of the difference in insulin sensitivity. More visceral fat contributed to lower insulin sensitivity independent of FRDA. Insulin secretion accounting for sensitivity (disposition index) was not different.

CONCLUSIONS

Lower mitochondrial OXPHOS capacity, inactivity, and visceral adiposity contribute to lower insulin sensitivity in FRDA. Higher insulin secretion appears compensatory, and when inadequate, could herald DM. Further studies are needed to determine if muscle- or adipose-focused interventions could delay FRDA-related DM.

Surrogate measures of first-phase insulin secretion versus reference methods intravenous glucose tolerance test and hyperglycemic clamp: a systematic review and meta-analyses

INTRODUCTION

In this systematic review, we investigated the diagnostic accuracy of surrogate measures of insulin secretion based on fasting samples and the oral glucose tolerance test (OGTT). The first phase of insulin secretion was calculated using two gold standard methods; the hyperglycemic clamp (HGC) test and intravenous glucose tolerance test (IVGTT).

RESEARCH DESIGN AND METHODS

We conducted searches in the PubMed, Cochrane Central, and Web of Science databases, the last of which was conducted at the end of June 2021. Studies were included that measured first-phase insulin secretion in adults using both a gold-standard reference method (either HGC or IVGTT) and one or more surrogate measures from either fasting samples, OGTT or a meal-tolerance test. QUADAS-2, a revised tool for the quality assessment of diagnostic accuracy studies, was used for quality assessment. Random-effects meta-analyses were performed to examine the correlation between first-phase measured with gold standard and surrogate methods.

RESULTS

A total of 33 articles, encompassing 5362 individuals with normal glucose tolerance, pre-diabetes or type 2 diabetes, were included in our systematic review. Homeostatic model assessment (HOMA)-beta and Insulinogenic Index 30 (IGI(30)) were the surrogate measures validated in the largest number of studies (17 and 13, respectively). HOMA-beta's pooled correlation to the reference methods was 0.48 (95% CI 0.40 to 0.56) The pooled correlation of IGI to the reference methods was 0.61 (95% CI 0.54 to 0.68). The surrogate measures with the highest correlation to the reference methods were Kadowaki (0.67 (95% CI 0.61 to 0.73)) and Stumvoll's first-phase secretion (0.65 (95% CI 0.58 to 0.71)), both calculated from an OGTT.

CONCLUSIONS

Surrogate measures from the first 30 min of an OGTT capture the first phase of insulin secretion and are a good choice for epidemiological studies. HOMA-beta has a moderate correlation to the reference methods but is not a measure of the first phase specifically.

PROSPERO REGISTRATION NUMBER

The meta-analysis was registered at PROSPERO (Id: CRD42020169064) before inclusion started.

A machine learning-based classification of adult-onset diabetes identifies patients at risk of liver-related complications

Background & aims

Diabetes mellitus is a major risk factor for fatty liver disease development and progression. A novel machine learning method identified five clusters of patients with diabetes, with different characteristics and risk of diabetic complications using six clinical and biological variables. We evaluated whether this new classification could identify individuals with an increased risk of liver-related complications.

Methods

We used a prospective cohort of patients with a diagnosis of type 1 or type 2 diabetes without evidence of advanced fibrosis at baseline recruited between 2000 and 2020. We assessed the risk of each diabetic cluster of developing liver-related complications (i.e. ascites, encephalopathy, variceal haemorrhage, hepatocellular carcinoma), using competing risk analyses.

Results

We included 1,068 patients, of whom 162 (15.2%) were determined to be in the severe autoimmune diabetes subgroup, 266 (24.9%) had severe insulin-deficient diabetes, 95 (8.9%) had severe insulin-resistant diabetes (SIRD), 359 (33.6%) had mild obesity-related diabetes, and 186 (17.4%) were in the mild age-related diabetes subgroup. In multivariable analysis, patients in the SIRD cluster and those with excessive alcohol consumption at baseline had the highest risk for liver-related events. The SIRD cluster, excessive alcohol consumption, and hypertension were independently associated with clinically significant fibrosis, evaluated by liver biopsy or transient elastography. Using a simplified classification, patients assigned to the severe and mild insulin-resistant groups had a three- and twofold greater risk, respectively, of developing significant fibrosis compared with those in the insulin-deficient group.

Conclusions

A novel clustering classification adequately stratifies the risk of liver-related events in a population with diabetes. Our results also underline the impact of the severity of insulin resistance and alcohol consumption as key prognostic risk factors for liver-related complications.

Impact and implications

Diabetes represents a major risk factor for NAFLD development and progression. This study examined the ability of a novel machine-learning approach to identify at-risk diabetes subtypes for liver-related complications. Our results suggest that patients that had severe insulin resistance had the highest risk of liver-related outcomes and fibrosis progression. Moreover, excessive alcohol consumption at the diagnosis of diabetes was the strongest risk factor for developing liver-related events.

Development of a novel method for analysing N-acetyl-DL-leucine enantiomers in human fingernail by UPLC-ESI-MS/MS and the evaluation in diabetes mellitus

BACKGROUND

Recent research has been reported that N-acetyl-leucine content is significantly reduced in the saliva of diabetic patients, but no reports of detection in human nails have been found. This study aims to develop a novel method for the chiral separation of N-acetyl-DL-leucine (Ac-DL-Leu) in human fingernails to investigate the differences between healthy volunteers (HVs), prediabetes (PDs) and diabetic patients (DPs), and to verify its effectiveness in early warning of diabetes.

METHOD

Chiral resolution was performed using DBD-Apy pre-column derivatization on a C18 column (2.1 × 150 mm, 1.9 μm) at 40 ^oC, and detected by UPLC-ESI-MS/MS.

RESULTS

The resolution and the limit of detection (LOD) of Ac-DL-Leu were 1.75 and 1.50 fmol, respectively. The linear range of Ac-DL-Leu was 10-2000 fmol and the determination coefficient (R²) was above 0.9997. The recovery of Ac-DL-Leu in human nails was 96.92-105.69%. The contents of Ac-D-Leu and Ac-L-Leu were analyzed in 18 HVs, 13 PDs and 16 DPs fingernails. The results showed that their contents were significantly lower in DPs than in PDs and HVs (p < 0.0001).

CONCLUSIONS

A method for evaluating the effectiveness of Ac-DL-Leu enantiomers in human fingernails as a biomarker for diabetes was firstly developed.

Omaveloxolone: an activator of Nrf2 for the treatment of Friedreich ataxia

INTRODUCTION

Friedreich ataxia (FRDA) is a rare autosomal recessive degenerative disorder characterized by ataxia, dysarthria, diabetes, cardiomyopathy, scoliosis, and occasionally vision loss in late-stage disease. The discovery of the abnormal gene in FRDA and its product frataxin has provided insight into the pathophysiology and mechanisms of treatment.

AREAS COVERED

Although the neurologic phenotype of FRDA is well defined, there are currently no established pharmacological treatments. Omaveloxolone, a nuclear factor erythroid 2-related factor 2 (Nrf2) activator, is currently under review by the Food and Drug Administration (FDA) and has the potential to be the first approved treatment for FRDA. In the present report, we have reviewed the basic and clinical literature on Nrf2 deficiency in FRDA, and evidence for the benefit of omaveloxolone.

EXPERT OPINION

The present perspective suggests that omaveloxolone is a rational and efficacious therapy that is possibly disease modifying in treatment of FRDA.

Friedreich ataxia: clinical features and new developments

Friedreich's ataxia (FRDA), a neurodegenerative disease characterized by ataxia and other neurological features, affects 1 in 50,000-100,000 individuals in the USA. However, FRDA also includes cardiac, orthopedic and endocrine dysfunction, giving rise to many secondary disease characteristics. The multifaceted approach for clinical care has necessitated the development of disease-specific clinical care guidelines. New developments in FRDA include the advancement of clinical drug trials targeting the NRF2 pathway and frataxin restoration. Additionally, a novel understanding of gene silencing in FRDA, reflecting a variegated silencing pattern, will have applications to current and future therapeutic interventions. Finally, new perspectives on the neuroanatomy of FRDA and its developmental features will refine the time course and anatomical targeting of novel approaches.

Friedreich's Ataxia related Diabetes: Epidemiology and management practices

AIMS

Friedreich's Ataxia (FRDA) is a progressive neuromuscular disorder typically caused by GAA triplet repeat expansions in both frataxin gene alleles. FRDA can be complicated by diabetes mellitus (DM). The objective of this study was to describe the prevalence of, risk factors for, and management practices of FRDA-related DM.

METHODS

FACOMS, a prospective, multi-site natural history study, includes 1,104 individuals. Extracted data included the presence of DM and other co-morbidities, genetic diagnosis, and markers of disease severity. We performed detailed medical record review and a survey for the subset of individuals with FRDA-related DM followed at one FACOMS site, Children's Hospital of Philadelphia.

RESULTS

FRDA-related DM was reported by 8.7% of individuals. Age, severe disease, and FRDA cardiac complications were positively associated with DM risk. FRDA-related DM was generally well-controlled, as reflected by HbA1c, though diabetic ketoacidosis did occur. Insulin is the mainstay of treatment (64-74% overall); in adults, metformin use was common and newer glucose-lowering agents were used rarely.

CONCLUSIONS

Clinical factors identify individuals at increased risk for FRDA-related DM. Future studies should test strategies for FRDA-related DM screening and management, in particular the potential role for novel glucose-lowering therapies in preventing or delaying FRDA-related cardiac disease.

Determination of N-acetyl-DL-leucine in the saliva of healthy volunteers and diabetic patients using ultra-performance liquid chromatography with fluorescence detection

BACKGROUND

Recent studies have indicated that N-acetyl-leucine (N-Ac-Leu) is a potential biomarker of diabetes. This study aimed to measure the levels of enantiomers of the chiral molecule N-Ac-DL-Leu in the saliva of patients with type 2 diabetes and further determine the potential association between them.

METHOD

A novel validated method was established using ultra-performance liquid chromatography (UPLC) with fluorescence (FL) detection, in which precolumn derivatization of (R)-(-)-4-(N, N-dimethylaminosulfonyl)-7-(3-aminopyrrolidin-l-yl)-2,1,3-benzoxadiazole [(R)-(-)-DBD-APy] was used for the simultaneous determination and chiral separation of N-Ac-DL-Leu in human saliva.

RESULTS

The labeled N-Ac-DL-Leu diastereomers were completely separated, with a resolution value of 1.93. Additionally, excellent linearity for N-Ac-DL-Leu was observed, with high coefficients of correlation (r² ≥ 0.9999) in the range of 10-300 μM; the limit of quantitation (signal-to-noise ratio=10) was 40-120 pmol/mL, and the mean recoveries of N-Ac-L-Leu and N-Ac-D-Leu were 102.48% and 104.68%, respectively. The levels of N-Ac-Leu in the saliva of diabetic patients and healthy volunteers were determined, and it was found that the levels of N-Ac-DL-Leu in the saliva of diabetic patients were significantly lower than those in healthy volunteers. (p < 0.01).

CONCLUSIONS

The proposed method was successfully applied for the measurement of N-Ac-DL-Leu enantiomers in the saliva of diabetic patients and healthy volunteers.

Polyuria and Acute Hyperglycemia Secondary to New-Onset Diabetes in a Young Woman With Friedreich's Ataxia

A 23-year-old woman with progressive Friedreich's ataxia (FRDA) presented to a local urgent care facility for urinary urgency and frequency. A urinalysis showed the presence of trace ketones and glucose, and point-of-care testing revealed severely elevated glucose. The patient was referred to the emergency department and was admitted for further evaluation of hyperglycemia. Laboratory tests were negative for a urinary tract infection; however, results revealed elevated serum glucose and hemoglobin A1C. She was diagnosed with new-onset diabetes mellitus and started on insulin therapy. Management of her diabetes was complicated due to advanced neurodegenerative symptoms related to FRDA. An individualized treatment plan and coordination of care with her home facility were essential for managing her diabetes.