Insulin sensitivity and lipolysis in adolescent girls with poorly controlled type 1 diabetes: effect of anticholinergic treatment

Plasma exosomal proteomic studies of corneal epithelial injury in diabetic and non-diabetic group

OBJECTIVE

Diabetic Keratopathy (DK) is one of the significant complications of type II diabetes (T2DM) with pathogenesis not yet clarified. Since hyperglycemia is able to change the protein components contained in plasma exosomes, liquid chromatography-tandem mass spectrometry (LC-MS/MS) is considered as feasible to analyze the expression of plasma exosomal proteins in patients with T2DM and non-diabetic patients respectively, find critical biological markers, and explore the mechanism of DK as well as potential therapeutic targets.

METHOD

Blood and clinical information of corneal epithelial injury in a diabetic group (the study group) and a non-diabetic group (the control group), who were patients admitted to the Department of Ophthalmology, Yangpu Hospital, Tongji University School of Medicine from July 2020 to November 2020, were collected. The qEV size exclusion method was adopted to separate exosomes from plasma. The exosomes were then identified through transmission electron microscopy (TEM), nanoparticle tracking analyzer (NTA), and Western blot. The plasma exosomes of the study group and the control group were quantitatively analyzed by proteomics. A bioinformatics method is utilized to screen differential proteins and the expression of the differential proteins was verified by Western blot.

RESULT

TEM indicated that the exosomes had a double-concave disc-like appearance, with a size of about 100 nm, and Western blot expressed as CD63 and TSG101. The plasma exosomes of the study group and the control group were analyzed by quantitative proteomics with a total number of 952 proteins detected of which 245 proteins existed in the ExoCarta exosomal protein database. Through adoption of P-value to screen credible differential proteins, the heat map displayed 28 differential proteins, 7 upregulated proteins, and 21 downregulated proteins; the volcano map displayed 7 upregulated proteins and 22 downregulated proteins; the PPI interaction map displayed 12 upregulated proteins and 18 downregulated proteins. Through GO enrichment analysis, it was identified that the differential protein participated in the main biological processes and was involved in regulating the cell's stimulation response to insulin, the insulin receptor signaling pathway, and the activity of glycosylphosphatidylinositol phospholipase D as well as anti-oxidation. The enriched cell components include main components such as exosomes, blood particles, and cytoplasm. KEGG enrichment analysis indicated that the target protein FLOT2 was mainly concentrated in insulin-related signaling pathways. Western blot indicated that the expression of FLOT2 in the study group was lower compared with the control group while the expression of Exo70 was higher.

CONCLUSION

Proteomic analysis of the study group and the control group displayed a variety of proteins in plasma exosomes. The downregulated protein FLOT2 in the study group was closely related to the occurrence, development, and complication of DK in T2DM patients. The expression status of plasma FLOT2 protein in T2DM patients is expected to be a biomarker for diagnosing and monitoring of DK.

Chronic conditions in adolescents

The health problems related to the nervous system are on rise in young infants leading to high mortality amongst this age group. A chronic medical condition (CC) is present in this age group to the tune of 10–20%. We searched the electronic database PubMed for pre-clinical as well as clinical controlled trials reporting variable chronic conditions especially in pediatric patients. Most of these reports revealed that type 1 diabetes mellitus is the most common CC in young infants. In female patients, metabolic control is often disturbed during CC in this age group. Poor metabolism regulation often results in long-term complications, including cognitive disorders. In cognitive disorders, memory loss and learning problems are the most among adolescents. Executive problems are observed to be associated with low physical activities. The review article concludes that knowledge about factors influencing treatment adherence is crucial in chronically ill infants. Further, we should focus on protective factors in order to prevent health risk behavior.

Increased and early lipolysis in children with long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency during fast

Children with long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHAD) have a defect in the degradation of long-chain fatty acids and are at risk of hypoketotic hypoglycemia and insufficient energy production as well as accumulation of toxic fatty acid intermediates. Knowledge on substrate metabolism in children with LCHAD deficiency during fasting is limited. Treatment guidelines differ between centers, both as far as length of fasting periods and need for night feeds are concerned. To increase the understanding of fasting intolerance and improve treatment recommendations, children with LCHAD deficiency were investigated with stable isotope technique, microdialysis, and indirect calometry, in order to assess lipolysis and glucose production during 6 h of fasting. We found an early and increased lipolysis and accumulation of long chain acylcarnitines after 4 h of fasting, albeit no patients developed hypoglycemia. The rate of glycerol production, reflecting lipolysis, averaged 7.7 ± 1.6 µmol/kg/min, which is higher compared to that of peers. The rate of glucose production was normal for age; 19.6 ± 3.4 µmol/kg/min (3.5 ± 0.6 mg/kg/min). Resting energy expenditure was also normal, even though the respiratory quotient was increased indicating mainly glucose oxidation. The results show that lipolysis and accumulation of long chain acylcarnitines occurs before hypoglycemia in fasting children with LCHAD, which may indicate more limited fasting tolerance than previously suggested.

Insulin resistance in adolescents with type 1 diabetes and its relationship to cardiovascular function

CONTEXT

Cardiovascular disease is the major cause of death in adults with diabetes, yet little is specifically known about the effects of type 1 diabetes (T1D) on cardiovascular outcomes in youth. Although insulin resistance (IR) likely contributes to exercise and cardiovascular dysfunction in T2D, IR is not typically considered a contributor in T1D.

OBJECTIVE

We hypothesized that cardiopulmonary fitness would be reduced in T1D youth in association with IR and cardiovascular dysfunction.

DESIGN AND PARTICIPANTS

This cross-sectional study at an academic hospital included 12 T1D adolescents compared with 12 nondiabetic controls, similar in age, pubertal stage, activity level, and body mass index.

OUTCOME MEASURES

Cardiopulmonary fitness was measured by peak oxygen consumption (VO(2)peak) and oxygen uptake kinetics (VO(2)kinetics), IR by hyperinsulinemic clamp, cardiac function by echocardiography, vascular function by venous occlusion plethysmography, intramyocellular lipid by magnetic resonance spectroscopy, and body composition by dual-energy x-ray absorptiometry.

RESULTS

T1D adolescents had significantly decreased VO(2)peak, peak work rate, and insulin sensitivity compared with nondiabetic adolescents. T1D youth also had reduced vascular reactivity and evidence of diastolic dysfunction and left ventricular hypertrophy. Despite their IR and reduced cardiovascular fitness, T1D youth had paradoxically normal intramyocellular lipid, waist to hip ratio, and serum lipids and high adiponectin levels. In multivariate analysis, IR primarily, and forearm blood flow secondarily, independently predicted VO(2)peak.

CONCLUSIONS

T1D youth demonstrated IR, impaired functional exercise capacity and cardiovascular dysfunction. The phenotype of IR in T1D youth was unique, suggesting a pathophysiology that is different from T2D, yet may adversely affect long-term cardiovascular outcomes.

[Adjunctive therapies to glycaemic control of type 1 diabetes mellitus]

Since Diabetes Control and Complications Trial (DCCT), intensive therapy has been directed at achieving glucose and glycosylated hemoglobin (HbA1c) values as close to normal as possible regarding safety issues. However, hyperglycemia (especially postprandial hyperglycemia) and hypoglicemia continue to be problematic in the management of type 1 diabetes. The objective of associating other drugs to insulin therapy is to achieve better metabolic control lowering postprandial blood glucose levels. Adjunctive therapies can be divided in four categories based on their mechanism of action: enhancement of insulin action (e.g. the biguanides and thiazolidinediones), alteration of gastrointestinal nutrient delivery (e.g. acarbose and amylin) and other targets of action (e.g. pirenzepine, insulin-like growth factor I and glucagon-like peptide-1). Many of these agents have been found to be effective in short-term studies with decreases in HbA1c of 0.5-1%, lowering postprandial blood glucose levels and decreasing daily insulin doses.

A novel minimal model to describe NEFA kinetics following an intravenous glucose challenge

Dynamics of nonesterified fatty acid (NEFA) metabolism in humans requires quantification if we are to understand the etiology of such diseases as type 1 and 2 diabetes, as well as metabolic syndrome and obesity, or if we are to elucidate the mechanism of action of various interventions. We present a new compartmental model that employs the pattern of plasma glucose concentrations in healthy young adults to predict dynamic changes that occur in plasma NEFA concentrations during either a glucose-only intravenous glucose tolerance test, or an insulin-modified intravenous tolerance test, or a modified protocol during which variable-rate glucose infusions were administered to prevent plasma glucose from declining below 100 mg/dl. The model described all of the major features of NEFA response to an intravenous glucose tolerance test, including an initial latency phase, a phase during which plasma NEFA concentrations plummet to a nadir, and a rebound phase during which plasma NEFA concentrations may rise to a plateau concentration, which may be substantially higher than the initial basal NEFA concentration. This model is consistent with physiological processes and provides seven adjustable parameters that can be used to quantify NEFA production (lipolysis) and utilization (oxidation). When tested on data from the scientific literature, the range in estimated rate of lipolysis was 24-36 micromol.l(-1).min(-1) and for NEFA oxidation rate was 25-54 micromol.l(-1).min(-1). All model parameters were well identified and had coefficients of variation < 15% of their estimated values. It is concluded that this model is suitable to describe NEFA kinetics in human subjects.

Fasting c-peptide and insulin-like growth factor-binding protein-1 levels help to distinguish childhood type 1 and type 2 diabetes at diagnosis

BACKGROUND

Children with new onset diabetes (n = 175) were evaluated over 12-months. Patients were presumptively diagnosed with type 2 diabetes mellitus (T2DM) (n = 26) based on obesity, a relative with T2DM, the ability to wean from insulin, and absence of glutamic acid decarboxylase-65 (GAD-65) antibodies. We hypothesized that markers of insulinization at diagnosis, including fasting C-peptide and insulin-like growth factor-binding protein (IGFBP)-1, in addition to initial CO(2) levels and urine ketones, would help in distinguishing type 1 diabetes mellitus (T1DM) from T2DM.

RESULTS

Children with T1DM (84 male, 65 female) had a mean age of 8.7 +/- 4.3 yr and a racial background of 78% white, 19% black, and 3% other. In contrast, children with T2DM (13 female, 13 male) had a mean age of 14.2 +/- 3.1 yr with a racial background of 58% black, 27% white, and 15% other. Fasting C-peptide level was 0.38 +/- 0.37 ng/mL in T1DM vs. 2.66 +/- 2.14 ng/mL in T2DM; a C-peptide of 0.85 ng/mL had 83% sensitivity in distinguishing T1DM from T2DM. Fasting IGFBP-1 level was 38.1 +/- 39.1 ng/mL (T1DM) vs. 3.6 +/- 4.5 ng/mL (T2DM); a value of 3.6 ng/dL could distinguish the two types of diabetes with 93% sensitivity. Urinary ketones were found in 79% of children with T1DM compared with 56% of those with T2DM, and the magnitude was associated with type of diabetes. Initial CO(2) level for T1DM was 17.9 +/- 6.9 mmol/L vs. 22.7 +/- 5.7 mmol/L for T2DM; a value of 21.5 mmol/L could distinguish the two types of diabetes with 83% sensitivity.

CONCLUSIONS

In addition to obesity, family history of T2DM, and absence of GAD-65 antibodies, children with new-onset T2DM may be distinguished from those with T1DM by a combination of biochemical parameters (C-peptide, IGFBP-1, CO(2), and urine ketones).

Increased lipolysis in LCHAD deficiency

An increasing number of fatty acid oxidation defects are being detected owing to diagnostic improvements and a greater awareness among clinicians. The metabolic block leads to energy disruption, fatty infiltration, and toxic effects on organ functions exerted by beta-oxidation metabolites. This investigation was undertaken to assess the influence of long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency on lipolysis and energy turnover. We addressed the question whether the lipolysis and glucose production rates would be altered in the fasting state in a child with this disease. Lipolysis, glucose production and resting energy expenditure (REE) were studied in a 17-month-old girl with LCHAD deficiency and her healthy twin sister. Lipolysis and glucose production were determined after a 4-6 h fast by constant-rate infusion of [1,1,2,3,3-(2)H(5)]glycerol and [6,6-(2)H(2)]glucose and analysis by gas chromatography-mass spectrometry. REE was estimated by indirect calorimetry. The affected girl showed 50% higher lipolysis than did her sister, whereas the glucose production rates were similar. Plasma levels of dicarboxylic acids of 6-12 carbon atoms chain length, 3-hydroxy fatty acids of 6-18 carbon atoms chain length, total free fatty acids, and acylcarnitines were increased in the patient, as was REE. Since glucose production rates and plasma glucose levels were similar in the two girls, the increased lipolysis observed in the patient probably represents a compensatory mechanism for energy generation. This is achieved at the price of an augmented risk for fatty acid infiltration and toxic effects of beta-oxidation intermediates. This highlights the importance of avoiding fasting in these patients.

Energy substrate production in infants born small for gestational age

AIM

To investigate energy substrate production and its hormonal regulation in infants born small for gestational age.

METHODS

Eleven infants, aged 24.4 +/- 5.3 hour, were studied following a fast of 4.0 +/- 0.6 hour. Gestational age was 35.4 +/- 2.8 weeks and birth weight 1804 +/- 472 g (<-2 SD). Rates of glucose production and lipolysis were analyzed using [6,6-(2)H(2)]-glucose and [2-(13)C]-glycerol.

RESULTS

Plasma levels of glucose and glycerol were 4.1 +/- 1.1 mmol x L(-1) and 224 +/- 79 micromol x L(-1), respectively. Glucose appearance averaged 30.3 +/- 8.2 and glucose production rate 21.1 +/- 6.1 micromol x kg(-1) x minutes(-1). Glycerol production rate was 5.6 +/- 1.6 micromol x kg(-1) x minutes(-1), correlating strongly to birth weight (r = 0.904, p < 0.001). Of the glycerol produced, 55 +/- 22% was converted to glucose, corresponding to 8 +/- 3% of the glucose production.

CONCLUSIONS

Even though the infants could produce energy substrates, lipolysis was reduced and the glucose production was in the low end of the normal range compared with infants born appropriate for gestational age. The correlation between glycerol production and birth weight indicates that lipolysis depends on the amount of stored fat. Data on insulin and insulin-like growth factor binding protein 1 support the view that insulin sensitivity in these infants is reduced in the liver but increased peripherally.

Decreased maternal lipolysis in intrauterine growth restriction in the third trimester

OBJECTIVE

Intrauterine growth restriction (IUGR) is a common complication of pregnancy. There are many possible aetiologic factors of maternal, placental and/or fetal origin. Often there is no known explanation. The aim of this study was to investigate whether a reduction in maternal energy substrate production could be one of the factors involved in IUGR.

DESIGN

Measurement of maternal energy substrate production and glucoregulatory hormones in women with growth-restricted fetuses.

SETTINGS

University Hospital, Uppsala, Sweden.

POPULATION

Ten healthy pregnant women with IUGR were compared with eight recently reported healthy women with normal pregnancies. The women were studied at 35.4+/-1.6 weeks of gestation after an overnight fast.

METHODS

Rates of glycerol and glucose production were analysed by gas chromatography/mass spectrometry following constant-rate infusion of [1,1,2,3,3-(2)H5]glycerol and [6,6-(2)H2]glucose.

MAIN OUTCOME MEASURE

Third trimester glycerol and glucose production.

RESULTS

Glycerol production, reflecting lipolysis, was lower in the women with IUGR than in those with normal pregnancies, 2.36+/-0.58 versus 3.06+/-0.66 micromol kg-1 minute-1 (P=0.033), whereas there was no difference in rate of glucose production (glucose production rate [GPR]), 12.1+/-1.5 versus 13.2+/-1.5 micromol kg-1 minute-1 (P=0.23). Plasma glycerol levels were increased in the women with IUGR (P=0.008).

CONCLUSIONS

Lipolysis is lower in pregnancies complicated by IUGR as compared with normal pregnancies. Increased lipolysis during pregnancy provides substrate for maternal energy metabolism, which spares glucose for the fetus. A reduced maternal production of energy substrate could be one of several factors underlying IUGR. A lack of relationship between insulin levels and either lipolysis or GPR suggests defective regulation of energy substrate production in this group of pregnant women.

Increased lipolysis in non-obese pregnant women studied in the third trimester

BACKGROUND

During pregnancy, metabolic adaptation takes place in the mother to provide for the supply of substrates to the growing fetus.

OBJECTIVE

To determine rates and endocrine regulation of lipolysis and glucose production (GPR) in late pregnancy.

DESIGN

Energy substrate production was measured in healthy pregnant women by use of stable isotope-labelled compounds.

SETTING

University Hospital, Uppsala, Sweden.

SAMPLE

Eight healthy non-obese, non-smoking women with normal pregnancies were studied at 33-36 weeks of gestation after an overnight (12-14 hours) fast.

METHODS

Rates of glycerol and glucose production were analysed by gas chromatography/mass spectrometry following constant rate infusion of [1,1,2,3,3-(2)H(5)]-glycerol and [6,6-(2)H(2)]-glucose.

MAIN OUTCOME MEASURE

Glycerol and glucose production in the third trimester.

RESULTS

The mean rate of glycerol production, reflecting lipolysis, was 3.06 (0.66) and the mean GPR was 13.2 (1.5) micromol kg(-1) minute(-1) [2.38 (0.27) mg kg(-1) minute(-1)]. There was a correlation between rate of glycerol production and GPR (r = 0.75, P = 0.033). Fasting insulin levels correlated inversely with both the rate of glycerol production (r = -0.85, P = 0.008) and GPR (r = -0.78, P= 0.021).

CONCLUSIONS

Our results show that lipolysis is markedly increased during late pregnancy compared with reported data for non-pregnant women. The data also confirm the occurrence of an increased GPR in pregnant women. The finding of a correlation between rate of glycerol production and GPR corroborates the view that lipolysis promotes gluconeogenesis. Although late gestation is associated with insulin resistance, the results show that insulin plays a regulatory role both in lipolysis and glucose production.

Potential Adjunctive Therapies in Adolescents with Type 1 Diabetes Mellitus

Appropriate insulin therapy is central to the management of all individuals with type 1 diabetes mellitus. The potential role of adjunctive therapy in type 1 diabetes is to improve insulin action, and facilitate the ability of all individuals with type 1 diabetes to achieve and maintain 'better' metabolic control. The landmark clinical trial in type 1 diabetes is the Diabetes Control and Complications Trial (DCCT). The DCCT showed that there is no threshold below which a reduction in glycemia would not provide further benefit against diabetes-related microvascular complications. This study in particular provides the rationale for attempting to achieve as near normoglycemia as possible. We review the use of recognized pharmacologic agents as potential insulin adjunctives in children and adolescents with type 1 diabetes. Adjunctive therapies can be grouped into the following categories based on their putative mechanism of action: enhancement of insulin action (e.g. the biguanides and thiazolidinediones), alteration of gastrointestinal nutrient delivery (e.g. acarbose and amylin), and other targets of action (e.g. pirenzepine and insulin-like growth factor-1 [IGF-1], which reduce growth hormone secretion, and glucagon-like peptide-1, which acts to stimulate insulin secretion). Many of these agents have been found to be effective in short-term studies with decreases in glycosylated hemoglobin of 0.5-1.0%, lowered postprandial blood glucose levels, and decreased daily insulin doses. Adverse effects such as poor gastrointestinal tolerability (metformin, acarbose) or potential acceleration of retinopathy (IGF-1) indicates the need for further studies of efficacy, safety, and patient selection before these adjunctive therapies can be widely recommended in type 1 diabetes.