Normal adiponectin levels despite abnormal glucose tolerance (or diabetes) and inflammation in adult patients with cystic fibrosis

A cross-sectional study in adiponectin, glucose metabolism, and body composition in cystic fibrosis

Objective

We hypothesized that the insulin-sensitizing adipokine adiponectin (ADP) is upregulated in cystic fibrosis (CF) related diabetes (CFRD) and underweight adults with CF. We aimed to assess correlations between glucose metabolism, body composition and ADP in CF.

Methods

We performed a cross-sectional study among adults with CF at the Copenhagen CF Center. The study included a fasting level of ADP, an oral glucose tolerance test (OGTT), and a dual energy-x-ray absorptiometry scan.

Results

In total, 115 patients were included of whom 104 had an OGTT performed. Glucose intolerance was not correlated with ADP in multivariable analysis, while increased hepatic insulin resistance (i.e., HOMA-IR) was correlated with reduced ADP levels. ADP declined by 4% (eβ 0.96, 95% CI: 0.94, 0.98), 5% (eβ 0.95, 95% CI: 0.93, 0.98), 9% (eβ 0.91, 95% CI: 0.87, 0.95), and 83% (eβ 0.17, 95% CI: 0.08, 0.37) for each one unit (kg/m2) increase in body mass index, fat mass index, muscle mass index, and bone mineral content index, respectively.

Conclusions

In CF, ADP was negatively correlated with hepatic insulin resistance as well as low fat, muscle, and bone mass, but not with glucose intolerance. This suggests that malnutrition leads to higher ADP levels in CF.

Cystic fibrosis-related diabetes develops from a combination of insulin secretion defects and insulin resistance

AIM

The relative contributions of insulin secretory defects and possible additional contribution of insulin resistance for the development of cystic fibrosis (CF)-related diabetes (CFRD) are poorly understood. We aimed to (a) determine which indices of insulin resistance predict progression to CFRD, and (b) to model the relative contributions of insulin secretory function and insulin resistance to predict the risk of CFRD.

MATERIALS AND METHODS

Three hundred and three individuals living with CF underwent a 2-h oral glucose tolerance test with blood sampling every 30 min at 12-24-month intervals until they developed CFRD or until the end of follow-up (up to 15 years). Indices of insulin resistance (e.g. Stumvoll) and insulin secretion were calculated from oral glucose tolerance test glucose and insulin measurements. CFRD-free survival was assessed by survival analysis.

RESULTS

Estimated insulin resistance showed associations with glucose homeostasis and risk of progression to CFRD. The CFRD-free survival was significantly different between quartiles of insulin resistance (p < 0.0001). When patients were subdivided according to both insulin resistance and insulin secretion (insulinogenic index), CFRD-free survival was significantly lower in those with combined lowest insulin secretion and highest insulin resistance (Stumvoll) indices (hazard ratio: 11.2; p < 0.0001). There was no significant difference when the same analysis was performed for the nine other indices.

CONCLUSIONS

Insulin resistance is correlated with glucose homeostasis and the risk of progression to CFRD. Patients combining low insulin secretion and high insulin resistance had the greatest odds of developing CFRD over a 15-year period.

Changes of androgen and corticosterone metabolites excretion and conversion in cystic fibrosis

Cystic fibrosis (CF) is a life-threatening inherited disease related to a mutation in the CFTR gene, that leads to serious health complications such as chronic pulmonary infections, pancreatic insufficiency, dysfunction of the sweat glands and reproductive system. For the first time, we have described the profile of corticosterone and androgen metabolites in urine, as well as the activity of enzymes involved in steroid genesis and metabolism in people with CF, using gas chromatography/mass spectrometry. A significant reduction in the excretion of most of the measured metabolites in CF was found. These differences were observed in the group of progestagen metabolites, as well as among metabolites of corticosterone and androgens. We revealed higher activities of 17β-hydroxysteroid dehydrogenase and 17,20-lyase in the Δ4 pathway compared with controls, what can promote the androgen synthesis through the backdoor androgen pathway. We have also found the increased conversion activity of 11-oxyganated steroids by 5a-reductase in backdoor pathway. Levels of the most potent and vital androgens (testosterone and dihydrotestosterone) are comparable in both groups. However, the excretion of dehydroepiandrosterone was lower in CF. Decreased cholesterol lipoprotein levels may contribute to limited intracellular cholesterol supply and reduced adrenal steroidogenesis in CF individuals. Changes in the activity of some steroidogenesis enzymes may suggest the presence of some peripheral adaptive mechanisms in CF to maintain androgen balance in the body despite the limited sufficiency of secretion by the adrenal cortex.

Alteration in glucocorticoids secretion and metabolism in patients affected by cystic fibrosis

Cystic fibrosis (CF) is an inherited syndrome associated with a mutation in a cystic fibrosis transmembrane conductance regulator gene, composed of exocrine gland dysfunction involving multiple systems that may result in chronic respiratory infections, pancreatic enzyme deficiency, and developmental disorders. Our study describes for the first time the urinary profile of glucocorticoid metabolites and the activity of the enzymes involved in the development and metabolism of cortisol in patients with CF, using a gas chromatography/mass spectrometry method. Data were obtained from 25 affected patients and 70 sex- and age- matched healthy volunteers. We have shown a general decrease in the activity of enzymes involved in the peripheral metabolism of cortisol, such as 11β-hydroxysteroid dehydrogenase type 2, 5α- and 5β-reductases. In contrast, the activity of 11β-hydroxysteroid dehydrogenase type 1, the enzyme that converts cortisone to cortisol, increased. Furthermore, our study found a significant decrease in glucocorticoid excretion in patients with CF. This may suggest adrenal insufficiency or dysregulation of the HPA axis and the development of peripheral mechanisms to counteract cortisol degradation in the case of reduced synthesis of glucocorticoids by the adrenal glands. Furthermore, the activity of 5α-reductase seems to be enhanced only through the backdoor pathway, especially when we taking into consideration 11β-hydroxyandrosterone/11β-hydroxyetiocholanolone ratio which has been shown to be the best differential marker for enzyme activity. CF impairs nutritional effects and energetic balance in patients; thus, our findings suggest the existence of adaptive mechanisms due to limited secretion of adrenal steroids and subsequent diminished amounts of their metabolites in urine. On the other hand, local control of cortisol availability is maintained by enhanced 11βHSD1 activity and its recovery from cortisone in organs and tissues which need this. Steroid hormone dysregulation might be another important factor in the course of CF that should be taken into account when planning an effective and comprehensive therapy.

A negative screening of rare genetic variants in the ADIPOQ and STATH genes in cystic fibrosis

BACKGROUND

The phenotypic variability in cystic fibrosis (CF) is widely recognized and modulated by environmental and genetic factors, including CFTR pathogenic variants and modifier genes genetic variants. In this context, determining the presence of variants in genes involved in immune response may allow a better understanding of CF variability, mainly in lung disease. Thus, ADIPOQ and STATH genes were selected and the analysis of exons and exon/intron junctions was performed for the determination of variations in its sequence, to determine the possible genetic modulation.

METHODS

A total of 49 patients with CF, diagnosed for showing abnormal [chloride] levels in the sweat test, and identification of two pathogenic variants in CFTR categorized as class I and II were included. Genetic sequencing was performed for the identification of variants in the modifier genes.

RESULTS

In our analysis, there was absence of rare genetic variants in STATH and ADIPOQ genes associated with the clinical variability. Thus, we are not able to establish an association between the disease severity and rare genetic variants in STATH and ADIPOQ genes, considering exons and exon/intron junctions.

CONCLUSIONS

Considering the negative screening for rare genetic variants in ADIPOQ and STATH genes, it may be concluded that these genes are not associated with phenotypic modulation of CF in our population. To understand the modifier genes and its action at CF variability it is essential to promote a better overview of the disease. Also, negative reports can help to direct new studies without the use of unnecessary financial support.

Role of Serum Adiponectin and Vitamin D in Prediabetes and Diabetes Mellitus

OBJECTIVES

The roles of deficient or deranged insulin, adiponectin and 25 hydroxy vitamin D (25[OH]D) levels regulating food intake, energy metabolism, glucose and lipid metabolism and body weight have been reported in the pathogenesis of prediabetes and type 2 diabetes mellitus. However, their congruity in the etiology of diabetes mellitus is unknown. Thus, the aim of the study was to investigate the roles of these parameters together and to establish their interrelationship in patients with prediabetes and diabetes.

METHODS

The preliminary cross-sectional study included 77 persons with type 2 diabetes who were matched for age, sex and body mass index (BMI); 73 persons with prediabetes; and 52 healthy control subjects. Fasting serum levels of adiponectin, insulin and 25(OH)D were measured by commercially available immune assay kits, and routine biochemical parameters were analyzed in all study groups.

RESULTS

The results show statistically significant lower levels of serum adiponectin and serum 25(OH)D and higher serum insulin levels in persons with prediabetes or type 2 diabetes with respect to controls. The changes in the serum adiponectin or serum 25(OH)D in persons with prediabetes and type 2 diabetes were found to be inversely correlated with the serum levels of insulin. Moreover, multiple linear regression analysis, with 25(OH)D, insulin and homeostatic model assessment-insulin resistance (HOMA-IR) as the variables, revealed that serum adiponectin levels might be an independent risk factor for the progression of prediabetes and type 2 diabetes in subjects.

CONCLUSIONS

The association of these hormones might act as a significant predictor of progression of prediabetes to type 2 diabetes. Decreased serum adiponectin levels might be an independent risk factor for progression to prediabetes and type 2 diabetes, which may help in developing experimental models of the disease or in identifying biomarkers or disease-modifying drugs.

The 1-h oral glucose tolerance test glucose and insulin values are associated with markers of clinical deterioration in cystic fibrosis

AIMS

Cystic fibrosis (CF) is associated with the emergence of CF-related diabetes (CFRD). CFRD is associated with increased risk of accelerated weight and/or lung function loss (clinical degradation). Data in the CF pediatric population reported an association between higher 60-min oral glucose tolerance test (OGTT) plasma glucose values and reduced lung function. Our objective was to evaluate the relationship between the 60-min OGTT insulin and glucose values and markers of clinical degradation in adult patients with CF.

METHODS

This study was based on an ongoing observational cohort of CF adult patients (≥18 years). All patients underwent a 2-h OGTT with 30-min interval sample measurements. Plasma insulin and glucose levels were measured. Adult patients (N = 240) were categorized based on the 60-min OGTT median values of glucose (G60, 11.0 mmol/L) and/or insulin (I60, 43.4 μU/mL).

RESULTS

A negative association was observed between the 60-min OGTT glucose value and pulmonary function (FEV1; P = 0.001), whereas 60-min OGTT insulin values were positively associated with BMI (P = 0.004). Patients with high G60 values displayed lower FEV1 than patients with low G60 values (P = 0.025). Patients with higher I60 values demonstrated higher values of both FEV1 (P = 0.022) and BMI (P = 0.003) than patients with low I60 values. More importantly, when adjusting for BMI, the difference in FEV1 between both groups no longer existed (P = 0.166).

CONCLUSIONS

Both insulin and glucose values at 60-min OGTT are associated with indicators of clinical degradation in adult patients with CF. Future prospective analyses are essential in establishing the clinical utility of these indicators.

Glucose intolerance in cystic fibrosis as a determinant of pulmonary function and clinical status

BACKGROUND

Cystic fibrosis related diabetes (CFRD) is associated with a decrease in pulmonary function and nutritional status. We investigated the clinical significance of impaired glucose tolerance (IGT) in cystic fibrosis (CF) patients.

METHODS

Fifty-five CF patients (aged 22.8 ± 9.2 years, 29 males, mean FEV1 67.9 ± 22% predicted, mean BMI-SDS -0.23 ± 1.1) underwent a 2-h Oral Glucose Tolerance Test (OGTT) with 30-min interval measurements of glucose and insulin. Additional clinical and laboratory data were obtained from the medical charts.

RESULTS

Thirty-eight participants (69%) had normal glucose tolerance (NGT), 13 (23.7%) had IGT, and 4 (7.3%) had newly diagnosed CFRD. Compared to patients with NGT, patients with IGT had significantly lower BMI-SDS (-1.1 ± 0.8 vs. 0.1 ± 1.1, p<0.001), mean FEV1 (57 ± 19 vs. 74 ± 21% predicted, p<0.01), and albumin (3.9 ± 0.3 vs. 4.3 ± 0.2g/dl, p=0.004), and higher fibrinogen (376 ± 56 vs. 327 ± 48 g/dl, p=0.02). Patients with IGT had impaired β-cell function, with reduced first phase insulin secretion, a delayed insulin peak, and significantly lower total insulin secretion, HOMA-%B and insulinogenic index. Seven patients had HbA1c in the "diabetic" range (≥6.5%; 47.5 mmol/mol), however, HbA1c was not a sensitive or specific marker of glucose tolerance status.

CONCLUSIONS

IGT in CF patients is associated with increased inflammation and decreased nutritional status and pulmonary function.

Association between the level of circulating adiponectin and prediabetes: A meta-analysis

Aims/Introduction

Adiponectin has been proposed to have an essential role in the regulation of insulin sensitivity and metabolism, but previous studies on levels of adiponectin in prediabetes remain inconsistent. The present study aimed to assess the differences of adiponectin levels between prediabetes patients and healthy controls by carrying out a meta-analysis.

Materials and Methods

We carried out a systematic literature search of PubMed, EMBASE, and other databases for case–control studies and cohort studies measuring adiponectin levels in serum or plasma from prediabetes patients and healthy controls. The pooled weighted mean difference (WMD) and 95% confidence interval (CI) were used to estimate the association between adiponectin levels and prediabetes.

Results

Three cohort studies and 15 case–control studies with a total of 41,841 participants were included in the meta-analysis. The results showed that circulating adiponectin levels in prediabetes patients were significantly lower than that of healthy controls (WMD –1.694 μg/mL; 95% CI –2.151, –1.237; P < 0.001). Subgroup analysis showed more significant differences between prediabetes patients and healthy controls when the ratio of the homeostatic model assessment of insulin resistance was >2.12 (WMD −2.95 μg/mL; 95% CI –4.103, –1.806; P < 0.001) and average age was >60 years (WMD −2.20 μg/mL; 95% CI –3.207, –1.201; P < 0.001). Additionally, WMD in adiponectin showed a trend of direct correlation in subgroups of homeostatic model assessment of insulin resistance ratio, body mass index and age.

Conclusions

The present meta-analysis supports adiponectin levels in prediabetes patients being lower than that of healthy controls,indicating that the level of circulating adiponectin decreases before the onset of diabetes.

Impact of sex on insulin secretion in cystic fibrosis

CONTEXT

Cystic fibrosis-related diabetes is primarily due to a defect in insulin secretion. Women with cystic fibrosis (CF) are at higher risk of developing CF-related diabetes.

OBJECTIVE

The objective of the study was to examine sex differences in insulin and glucose homeostasis. We hypothesized that in CF, women would display lower insulin secretion than men.

DESIGN

This was a study based on an ongoing observational CF cohort with a mean follow-up of 19.9 ± 5.2 months.

SETTING

The study was conducted at the CF clinic of the Centre Hospitalier de l'Université de Montréal (Québec, Canada).

PATIENTS

From 230 adults with CF (123 men, 107 women) of similar age and functional pulmonary status, 104 retested after the follow-up. Age-matched healthy individuals (25 men, 19 women) were included in the study.

INTERVENTIONS

Participants underwent a 2-hour oral glucose tolerance test with 30-minute interval sample measurements.

MAIN OUTCOME MEASURE

Plasma insulin and glucose levels were measured.

RESULTS

Women with CF had higher overall insulin secretion as compared with men with CF (P ≤ .05) but similar to healthy women (P = .606). Men with CF had lower overall insulin secretion than healthy men (P = .020) and higher insulin sensitivity (P = .009) than women with CF. PATIENTS with CF displayed higher overall glucose excursions than healthy patients. Sex-related differences were still observed in the CF cohort after follow-up.

CONCLUSIONS

Surprisingly, in CF, adult women presented higher insulin secretion than adult men at a comparable level with what is observed in healthy individuals. Potential implications of this sex dimorphism in CF remain to be established.

Diagnosis of cystic fibrosis-related glucose abnormalities: Can we shorten the standard oral glucose tolerance test?

Adult patients with cystic fibrosis (APCF) are at high risk of developing impaired glucose tolerance (IGT) and CF-related diabetes (CFRD) and thus an annual screening with a 2-h oral glucose tolerance test (OGTT) is recommended. This population would greatly benefit from a simplified and harmless alternative to the standard OGTT. Thus, we aimed to compare the diagnostic values of HbA1c and glycemias at interval time points during the 2-h OGTT for IGT and CFRD detection in APCF. To do so, we conducted a cross-sectional analysis of 194 APCF with normal fasting plasma glucose values (≤ 7.0 mmol · L(-1)) who underwent a 2-h OGTT. Receivers operating characteristic area under the curves (ROC-AUC) were analyzed to assess the diagnostic value of HbA1c and intermediate OGTT glycemias using 2-h OGTT glycemia as reference. For both IGT and CFRD diagnoses, ROC-AUC values obtained from glycemia at 90 min were significantly higher than HbA1c and remaining intermediate glycemias (p < 0.001). The best 90-min OGTT cut-off values for these diagnoses were >9.3 mmol · L(-1) (IGT) and ≥ 11.5 mmol · L(-1) (CFRD). A 90-min OGTT glycemia might be a simplified alternative to 2-h OGTT glycemia for earlier glucose tolerance abnormalities diagnosis in APCF. This finding should be confirmed in other APCF cohorts and its predictive value should be established prospectively.

Serum concentrations of resistin and adiponectin and their relationship to insulin resistance in subjects with impaired glucose tolerance

OBJECTIVES

This study measured the serum concentrations of resistin and adiponectin in Chinese subjects with impaired glucose tolerance (IGT) and investigated their association with insulin resistance, metabolic parameters and circulating inflammatory markers.

METHODS

A total of 124 subjects participated in the study (44 with IGT and 80 with normal glucose tolerance [NGT]). Fasting serum concentrations of lipids, glucose, insulin and adipocytokines (resistin, adiponectin, leptin, tumour necrosis factor-α [TNF-α], interleukin-6 and C-reactive protein) were measured.

RESULTS

Serum resistin concentrations were similar in the IGT and NGT groups but were significantly higher in overweight/ obese IGT subjects than in those of normal weight. Serum adiponectin concentrations were significantly lower in the IGT group than in the NGT group. In the IGT group, resistin was positively correlated with age, body mass index and TNF-α, and adiponectin was correlated positively with high-density lipoprotein cholesterol and negatively with TNF-α and waist/hip ratio.

CONCLUSIONS

Circulating resistin is unlikely to be a major mediator of glucose tolerance in humans but it may have an inflammatory role in IGT. The data support the theory that circulating adiponectin has an anti-inflammatory and anti-insulin resistance function.

Adiponectin and inflammation: consensus and controversy

Circulating levels of adiponectin decrease with increasing visceral obesity and are lower in patients with type 2 diabetes, the metabolic syndrome, and cardiovascular disease compared with controls matched by body mass index. Several reports demonstrated anti-inflammatory effects of adiponectin. Because increased adipose tissue is associated with low-grade chronic inflammation and proinflammatory factors inhibit adiponectin production, the current hypothesis states that chronic inflammation associated with visceral obesity inhibits production of adiponectin, perpetuating inflammation. The negative correlation between adiponectin and markers of inflammation in the aforementioned conditions supports this hypothesis. In contrast with disorders typically associated with excess adiposity and positive energy balance, adiponectin levels are elevated--rather than decreased--in classic chronic inflammatory/autoimmune diseases that are unrelated to increased adipose tissue, such as rheumatoid arthritis, SLE, inflammatory bowel disease, type 1 diabetes, and cystic fibrosis. In these patients, adiponectin levels positively--rather than negatively--correlate with inflammatory markers. Furthermore, proinflammatory effects of adiponectin have been reported in tissues such as joint synovium and colonic epithelium. Thus, adiponectin is regulated in the opposite direction and may exert differential functions in classic versus obesity-associated inflammatory conditions. This article discusses this apparent paradox and presents possible alternative and/or complementary explanations.