HLA type,islet cell antibodies,and glucose intolerance in cystic fibrosis.

Impaired glucose tolerance, assessed by a raised glycated haemoglobin (HbA1) concentration, was found in 24 (39%) out of 61 patients with cystic fibrosis with an age range of 1-23 years. No correlation between age and HbA1 concentration was found indicating that factors other than progressive pancreatic fibrosis may be important in the aetiology. HLA typing, islet cell antibodies, and autoantibody screen were completed. Eighteen (75%) out of 24 patients with cystic fibrosis who had an impaired glucose tolerance had HLA-DR3 or HLA-DR4 antigens compared with 23 (62%) out of 37 patients with normal glucose tolerance. Islet cell antibodies were present in seven (15%) out of 46 patients with cystic fibrosis; the prevalence in a normal population is 0.5%. Five (25%) of the 20 patients with a raised HbA1 concentration were positive for islet cell antibodies compared with two (8%) out of the 26 with normal glucose tolerance. Six (86%) out of seven patients who were positive for islet cell antibodies had HLA-DR3 or HLA-DR4 antigens. There was no general autoantibody production. Islet cell antibodies may play a part in the development of glucose intolerance in some patients with cystic fibrosis by being produced in those who are genetically predisposed as part of an immune response to damaged pancreatic tissue.     

Oral glucose tolerance testing in cystic fibrosis: Correlations with clinical parameters and glycosylated haemoglobin determinations

In 48 patients (age 2–28 years) with documented cystic fibrosis, glucose tolerance was evaluated by means of an oral glucose tolerance test (OGTT) and repeated glycosylated haemoglobin (HbA1C) measurements. An impaired OGTT was found in 15 patients. Their degree of undernutrition and severity of lung and liver involvement were no different from those with normal glucose tolerance. The mean peak insulin concentration as well as the integrated insulin concentration during the OGTT were comparable with patients with normal glucose tolerance (GT) and those with an impaired tolerance (GI). The mean time to attain peak insulin levels was significantly delayed in the GI group. (117 min vs 86 minP<0.01). On initial testing, elevated HbA1C levels were found in 22 patients. Mean HbA1C levels in the GI group were higher than in the GT group *8.2% vs 7.5%P<0.01). The HbA1C levels at the moment of OGT testing were positively correlated with the glycaemic response during the OGTT. The repeated HbA1C measurements 1 year later were no different from the initial mean HbA1C values in both groups. Two GI patients with initial HbA1C levels of 7.5% and 11% respectively developed diabetes mellitus several months after testing. The need for serial HbA1C determinations in cystic fibrosis is questioned.     

Research of factors for glucose intolerance in mucoviscidosis]

Glucose tolerance has been assessed in cystic fibrosis (CF) children using HbA1C and plasma glucose and insulin determinations during an oral glucose tolerance test (OGTT), along with the determination of HLA-DR and islet-cell (ICA) and anti-insulin (IAA) antibodies. Of 49 patients (25 males, 24 females), aged 2 to 21 years (mean = 10.9 years), 29 had normal glucose tolerance (WHO criteria) during OGTT, 14 had impaired glucose tolerance (IGT) and 6 had an isolated hyperglycemia at 120 min. Fasting plasma glucose and HbA1C were significantly higher in IGT than in normoglycemic patients. However, these two parameters showed poor individual predictive value of disturbance in glucose tolerance. Of 14 patients with abnormal OGTT, 7 were aged below 10 years, with 2 as young as 5 years; 8 patients were females. HLA antigens characteristic of type I diabetes tended to be found less frequently in CF patients than in the general population: 9% were DR3, 7% were DR4 and none was DR3/DR4. There were no HLA differences according to glucose tolerance. ICA and IAA were respectively detected in only one patient. Stimulated plasma insulin was low but did not correlate with glucose tolerance. In conclusion, impaired glucose tolerance is common in cystic fibrosis and can be found early in life. Although insulin secretion is decreased in this population, it does not seem to be the only factor responsible for impaired glucose intolerance. The absence of the genetical and immunological characteristics of type I diabetes confirms that glucose intolerance in cystic fibrosis is due to other pathogenetic mechanisms.     

Glucose tolerance in cystic fibrosis.

Glucose tolerance was evaluated in 356 living and dead patients with cystic fibrosis who were recorded at the Danish Cystic Fibrosis Centre. Twenty two patients (6%) were treated elsewhere, 25 (7%) were unable, unwilling or too young (age less than 2 years) to participate; 309 patients (87%) were therefore eligible for the study of whom 99 (32%) were dead and 210 (68%) were alive. Of the dead patients, 13 also had diabetes mellitus (13%). Of the living patients (median age 14 years, range 2-40), nine (4%) were known to have diabetes and all were being treated with insulin. In the remaining 201 patients an oral glucose tolerance test (1.75 g/kg body weight, maximum 75 g) was carried out. A total of 155 patients (74%) had normal glucose tolerance, 31 (15%) had impaired glucose tolerance, and 15 (7%) had diabetes mellitus according to the WHO criteria. The percentage of glycated haemoglobin (HbA1c) (reference range 4.1-6.4%) increased significantly as glucose tolerance decreased: when glucose tolerance was normal the median was 5.2%; when it was impaired the figure was 5.5%; in patients whose diabetes was diagnosed by the oral glucose tolerance test it was 5.9%; and in patients already known to have diabetes mellitus it was 8.6%. The incidence and prevalence of impaired glucose tolerance and diabetes mellitus increased with age. From the age of 15 to 30 years the decrease in the prevalence of normal glucose tolerance was almost linear. Within this age span the proportion of patients with cystic fibrosis with normal glucose tolerance was reduced by roughly 5%/year. Only 35% (95% confidence interval (CI) 22 to 48%) of the patients with cystic fibrosis who were alive at the age of 25 years had normal glucose tolerance; 32% (95% CI 14 to 49%) were diabetic. The prevalence of glucose intolerance in cystic fibrosis is rapidly increasing with age; its potentially harmful effect on the prognosis of cystic fibrosis is of increasing importance as the length of survival of these patients increases.     

Glucose intolerance in children with cystic fibrosis

OBJECTIVE: To evaluate the relations among glucose intolerance, genotype, and exocrine pancreatic status in patients with cystic fibrosis (CF). STUDY DESIGN: Data on 335 patients <18 years of age were from the Toronto CF database. A modified oral glucose tolerance test was given to 94 patients 10 to 18 years of age without recognized CF-related diabetes. CF transmembrane conductance regulator mutations and exocrine pancreatic status were determined for all patients. RESULTS: CF-related diabetes was clinically recognized in 9 of 335 (2.7%) patients <18 years of age, all of whom were pancreatic insufficient, and 8 of 9 had severe (classes I through III) mutations on both alleles. The ninth patient had unidentified mutations. Although all patients given the oral glucose tolerance test were asymptomatic and had normal fasting blood glucose, 16 of 94 (17%) had impaired glucose tolerance and 4 of 94 (4.3%) had CF-related diabetes without fasting hyperglycemia. Abnormal glucose tolerance was associated exclusively with severe mutations and exocrine pancreatic insufficiency. Glycosylated hemoglobin (HbA(1)C) levels did not correlate with glucose tolerance results. CONCLUSIONS: Screening of pancreatic-insufficient, adolescent patients with CF identified more with abnormal oral glucose tolerance than was suspected clinically and is recommended as a routine practice. HbA(1)C was not useful in screening for CF-related glucose intolerance.     

Longitudinal evaluation of glucose tolerance and insulin secretion in non-diabetic children and adolescents with cystic fibrosis: results of a two-year follow-up

Thirty-two patients with cystic fibrosis and repeatedly normal fasting blood glucose underwent oral glucose tests and islet-cell antibody assessments on two occasions approximately two years apart. Fourteen patients underwent two iv glucose tolerance tests also. Although in the group as a whole mean glucose areas in response to the oral test remained substantially unmodified over the two-year period, the prevalence of glucose tolerance abnormalities increased from 37.5 to 50%. Insulin output in response to both oral and iv tolerance tests decreased over time. Worsening of insulin secretion and/or of glucose tolerance was never accompanied by deteriorating clinical status. Islet-cell antibodies were detected in no patients, even in those who developed a diabetic glucose tolerance. These results support, on a longitudinal basis, the view of a progressive impairment of B-cell function in cystic fibrosis, which may precede the onset of metabolic abnormalities and is not triggered by autoimmunity.     

Low prevalence of glucose intolerance in racially mixed children with cystic fibrosis

Alves C, Lima DS, Cardeal M, Santana A. Low prevalence of glucose intolerance in racially mixed children with cystic fibrosis. Objective: To evaluate glucose tolerance in racially mixed Brazilian youth with cystic fibrosis (CF). Methods: Cross‐sectional study conducted between August and September 2007, at a reference service for CF, evaluating: glycated hemoglobin (HbA1c), blood glucose, and insulin levels, before and 2 h after a glucose overload. Results: There were 46 patients aged between 6 yr and 16 yr and 2 months (median: 9 yr and 10 months) of whom 64% were boys. Of these, 26% were Whites; 54.4% Mulattoes; and 19.6% Blacks. HbA1c was normal in all patients. Only one participant (12‐yr old) had glucose intolerance. Insulin levels ranged from 1 to 23 µIU/mL (median: 4.5 µIU/mL) at baseline and from 3.2 to 192.1 µIU/mL (median: 11 µIU/mL) after a glucose overload. Insulin resistance evaluated by the HOMA index, stratified by sex and age, was present in three patients. The ΔF508 mutation was present in only 4.3% of the sample, all of them being heterozygous. Conclusions: The low prevalence of carbohydrate intolerance in this population is probably a result of their young age. Another possibility is the low frequency of the ΔF508 mutation. Although not conclusive, these data suggest that in addition to age, the genotype:phenotype ratio may influence the development of glucose intolerance in patients with CF.     

Early detection of impaired glucose tolerance in patients with cystic fibrosis and predisposition factors

INTRODUCTION: The number of patients with glucose tolerance alterations associated with cystic fibrosis (CF) has increased, probably due to the greater survival rate among sufferers of this disease. We studied impaired glucose tolerance (IGT) in patients with CF and investigated whether its appearance has any relationship with age, sex, genetic mutation and/or the degree of clinical involvement. We assessed the parameters that might allow early detection. PATIENTS AND METHODS: In 28 patients with CF (14 M, 14 F; aged 22 months to 18 years), sex, genetic mutation, nutritional status and the degree of pancreatic and pulmonary involvement were recorded. The metabolic study included glycosylated hemoglobin (HbA1c) determination, oral glucose tolerance test (OGTT) and intravenous glucose tolerance tests (IVGTT). RESULTS: In the patients with CF, 35.71% showed impaired glucose tolerance (IGT) and 3.57% had diabetes mellitus. The patients with IGT and CF were 3.2 years older than those with normal glucose tolerance (NGT; p<0.05), but no significant differences were found regarding sex, anthropometric measurements, percentage of pulmonary gammagraphic involvement, Shwachman-Kulczycki test or HbA1c. In the OGTT, the patients homozygous for the deltaF508 mutation had higher blood glucose values than the heterozygous group (p=0.03), but these values were not higher than those in patients with other mutations. During the OGTT, blood insulin values at 30' were reduced in patients with IGT compared to patients with NGT (p<0.02) and the insulin peak occurred at 100.9+/-24.3 min compared to 65.3+/-21.8, respectively (p<0.05). In the IVGTT, 82.14% of the patients had reduced insulin levels at 1 and 3 min (I1'+3'). No differences in the blood glucose levels during the OGTT were found between patients with normal I1'+3' values and patients with reduced values. CONCLUSIONS: A high percentage of patients with CF also present with IGT. This increases with age and is more common among patients homozygous for the deltaF508 mutation and is not related to clinical status. Alterations in the kinetics of insulin secretion play an important role in the appearance of IGT and CF. We suggest that the OGTT is a more sensitive method than IVGTT for identifying early alterations in CF-related diabetes mellitus.     

Cystic fibrosis serum pancreatic amylase. Useful discriminator of exocrine function

To develop a simple test for pancreatic exocrine function in patients with cystic fibrosis, we compared serum pancreatic amylase isoenzyme (P isoamylase) activity with the more complex standard tests of pancreatic function. Twenty-seven patients with cystic fibrosis, newborn to 46 years of age, were studied. All patients over 17 months old with evidence of pancreatic exocrine insufficiency, as manifested by abnormal duodenal secretions and/or abnormal 72-hour fecal fat absorption, had serum P isoamylase activity below the age-matched normal range; patients with adequate pancreatic function (aged 2 to 46 years) had P isoamylase activity in or above the normal range. Although both normal neonates and neonates with cystic fibrosis have very low levels of serum P isoamylase activity, in patients over 1 1/2 years of age serum P isoamylase activity may serve as a simple and useful discriminator of pancreatic exocrine function in patients with cystic fibrosis.     

Verbesserung der Glukosetoleranz von Patienten mit Zystischer Fibrose unter pseudomonaswirksamer Chemotherpie

Background. For many patients with cystic fibrosis impaired glucose tolerance or even diabetes mellitus is becoming relevant with growing age. The influence of an anti-Pseudomonas chemotherapy on glucose homeostasis of cystic fibrosis patients was investigated. Patients and methods. In fourteen cystic fibrosis patients aged between 7 and 35 years glucose tolerance was tested by standard oral glucose tolerance test in the beginning and at the end of a routine anti-Pseudomonas chemotherapy of fourteen days. Beside the blood glucose serum insulin was determinated. Results. According to the criteria of the American Diabetes Association three of the fourteen patients had an impaired glucose tolerance and another three had diabetes mellitus when tested at the beginning of anti-Pseudomonas chemotherapy. In four of these six patients glucose tolerance was normal at the end of the chemotherapy. Of the remaining two patients one fulfilled the criteria for impaired glucose tolerance and one for diabetes mellitus. In these patients insulin secretion was lower in the second test. Peak insulin was reached earlier while there was no significant improvement of early insulin response. Conclusion. The treatment of chronic airway infection in cystic fibrosis patients with impaired glucose tolerance or diabetes mellitus results in an improvement of glucose homeostasis by a better insulin sensitivity and less by improvement of early insulin response. In developing diagnostic protocols for screening of cystic fibrosis-related diabetes mellitus the impact of the concomitant therapy on glucose homeostasis should be considered.     

Slow-release insulin in cystic fibrosis patients with glucose intolerance: a randomized clinical trial

Minicucci L, Haupt M, Casciaro R, De Alessandri A, Bagnasco F, Lucidi V, Notarnicola S, Lorini R, Bertasi S, Raia V, Cialdella P, Haupt R. Slow‐release insulin in cystic fibrosis patients with glucose intolerance: a randomized clinical trial. Background: Early stages of glucose metabolism impairment are a period at risk in the long‐term prognosis of cystic fibrosis (CF). Slow‐release synthetic insulin glargine can be a therapeutic tool in this metabolic condition. Methods: In this phase 3 multicenter, controlled, two‐arm, randomized clinical study, glargine was administered up to a dosage of 0.15 U/kg/die for a period of 18 months. Primary endpoint was the improvement of nutritional status [body mass index (BMI) Z score], while glucose tolerance [hemoglobin A1c (HbA1C) and respiratory function (FEV1 predicted] improvement were the secondary endpoints. Results: Thirty‐four subjects (18 in the glargine arm and 16 in the control arm) were evaluated. Adherence to insulin treatment was excellent. No significant adverse events were reported. There were no significant differences in BMI, HbA1C and FEV1 values between the two groups nor within groups, except for HbA1C improvement in the glargine arm at month +18 (p = 0.04). Conclusions: Glargine treatment was well accepted and tolerated. No real efficacy in improving clinical and glycometabolic conditions was demonstrated. Further studies are necessary to test glargine at higher dosage and for a longer follow‐up period.     

Predicting islet yield in pediatric patients undergoing pancreatectomy and autoislet transplantation for chronic pancreatitis

Bellin MD, Blondet JJ, Beilman GJ, Dunn TyB, Balamurugan AN, Thomas W, Sutherland DER, Moran A. Predicting islet yield in pediatric patients undergoing pancreatectomy and autoislet transplantation for chronic pancreatitis. Background/Objective: Chronic pancreatitis (CP) in children is associated with significant morbidity and can lead to narcotic dependence. Total pancreatectomy (TP) may be indicated in refractory CP to relieve pain; simultaneous islet autotransplant (IAT) may prevent postsurgical diabetes. About half of pediatric patients are insulin independent 1 yr after IAT. Insulin independence correlates best with the number of islets available for transplantation (islet yield). Currently there is no known method to predict islet yield in a given patient. We assessed the ability of preoperative metabolic tests to predict islet yields in 10 children undergoing TP/IAT. Design/Methods: Hemoglobin A1c (HbA_1c) and mixed meal tolerance tests (MMTT) were obtained prior to surgery in 10 patients age ≤ 18 yr. Fasting glucose, C‐peptide, and creatinine were used to calculate the C‐peptide to glucose* creatinine ratio (CPGCR). C‐peptide peak and area under the curve (AUC) were determined from 2 h MMTT. Linear regressions were performed to predict islet yield from baseline test results. Results: Islet yield ranged from 7000 to 434 000 islet equivalents (IE) (mean 222 452 ± 148 697 IE). Islet yield was well predicted from body weight and fasting plasma glucose (R ² = 57%, adjusted for overfitting by bootstrap). Islet yield was positively associated with CPGCR, peak C‐peptide, and AUC C‐peptide and negatively associated with HbA_1c. Conclusions: Pilot data from 10 pediatric patients suggest that simple preoperative measurement of fasting plasma glucose may give a useful prediction of islet yield. Islet yield correlates with HbA_1c and C‐peptide levels. This information allows individual candidates to weigh the specific risk of becoming diabetic against the benefit of pain relief should they undergo TP‐IAT.     

Continuous glucose monitoring system in the screening of early glucose derangements in children and adolescents with cystic fibrosis

BACKGROUND: In cystic fibrosis (CF), diabetes mellitus (DM) is associated with progression of pulmonary disease and nutritional impairment. AIM: To compare oral glucose tolerance test (OGTT) and continuous glucose monitoring system (CGMS) in patients with CF with early glucose derangements. PATIENTS AND METHODS: Thirty-two patients with CF (5-20 years) with intermediate glucose values > 7.7 mmol/l during OGTT received a CGMS registration. Patients were classified into those with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and DM, according to glucose values at 120 min of OGTT and during CGMS. Furthermore BMI z-scores, forced expiratory volume in 1 second (FEV1%), number of respiratory infections/year, enzyme supplementation, and HbA1c were evaluated. RESULTS: OGTT and CGMS derangements were in agreement in 43.7% of the patients. BMI z-scores, FEV1%, number of respiratory infections/ year, enzyme supplementation, and HbA1c did not differ among the three groups. HbA1c, correlated positively with 120 min OGTT (r = 0.34; p = 0.059), CGMS area (r = 0.35; p = 0.048) and the number of respiratory infections, and negatively with FEV1%. CONCLUSIONS: Intermediate glucose values during OGTT should be considered as a screening test in patients with CF. CGMS can be useful in studying the early occurrence of glucose derangements in selected patients.     

Plasma immunoreactive endothelin levels in children with cystic fibrosis

Plasma immunoreactive endothelin levels were determined in 31 children and adolescents with cystic fibrosis and it was examined whether these levels correlated with the severity of the disease. The study comprised 16 cystic fibrosis patients (mean (SD) age 13.0 (4.9) y) with impaired lung function (Group A), 15 cystic fibrosis patients (11.2 (5.5) y) with unimpaired lung function (Group B) and 28 healthy controls (10.6 (4.3) y) (Group C). The selection and classification of patients into groups was based on criteria including the grade of finger-clubbing, the Brasfield chest radiograph score and spirometric and arterial blood gas values. In all subjects, plasma immunoreactive endothelin, atrial natriuretic peptide, renin, serum aldosterone levels and serum and urine electrolytes were measured. CONCLUSIONS: Plasma endothelin levels were significantly higher in Group A (range 2.5-8.4 pg/ml, median 3.2 pg/ml) than those in Group B (1.3-3.8 pg/ml, median 2.0 pg/ml, p < 0.001) and Group C (1.5-3.5 pg/ml, median 2.5 pg/ml, p < 0.001), whereas they did not differ between groups B and C. They correlated positively with the severity of finger-clubbing, heart rate, arterial blood PCO2, plasma atrial natriuretic peptide levels and serum aldosterone levels and negatively with the arterial blood PO2, forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1) and the Brasfield chest radiograph score. In multivariate regression analysis PO2 was the only independent factor found to significantly affect plasma endothelin levels. In conclusion, plasma immunoreactive endothelin levels are increased in cystic fibrosis patients with impaired pulmonary function and are related to the severity of the disease.     

GLUCOSE-GALACTOSE MALABSORPTION

In 2 children with glucose-galactose malabsorption the intermediate metabolism of hexoses was studied. The removal rate of injected glucose was slow when the diet of the children contained limited amounts of well absorbed carbohydrate (fructose). When sufficient fructose was given in the diet, the half-life of injected glucose was normal. A fast removal rate was seen when large amounts of carbohydrates had been administered prior to the intravenous GTT. The results of oral fructose tolerance tests varied with the pre-test diet in a similar manner. The fructosemia was small and independent of the diet, but the blood glucose concentration reacted in a way indicating decreased glucose tolerance if the diet contained little absorbable carbohydrate. This was evidently an unspecific effect of carbohydrate deprivation; in a control case, an infant with cystic fibrosis, initially malnourished, signs of decreased glucose tolerance were seen with an oral fructose tolerance test. In him, as well as in the patient with glucose-galactose malabsorption, the supranorma1 rise of blood glucose was abolished by dietary measures ensuring an ample supply of calories and carbohydrates. The intravenous galactose tolerance, tested in one of the patients, was probably normal at 13 months of age and certainly normal at 6 years of age. It is concluded that the observed abnormalities of the metabolism of glucose in patients with glucose-galactose malabsorption are unspecific for this disease and merely secondary to carbohydrate deprivation.     

Glucose homeostasis in mucoviscidosis

In patients with cystic fibrosis (CF) of the pancreas an endocrine imbalance especially of insulin secretion due to progressive structural abnormalities of the pancreas must be expected. 30-75 percent of CF-patient exhibit impaired oral glucose tolerance tests (oGTT). Deterioration of the glucose homeostasis leads to a secondary diabetes mellitus that mimics a type II diabetes in the early stage, in the later course of disease it resembles a type I diabetes with absolute insulinopenia. In this study glucose homeostasis was investigated after an oral glucose load with 1.75 g glucose/kg bodyweight. Glucose, C-peptide and insulin were measured during 180 minutes. 32 nondiabetic CF-patients were studied. 16 patients revealed an impaired oral glucose tolerance according to the criteria of the National Diabetes Data Group. 6 patients showed a normal glucose tolerance and 10 patients with normal fasting and 120 minute glucose concentrations were hyperglycemic at midtest determinations. Impaired oGTTs were observed in malnourished CF-patients in a higher rate than in normal weight patients. A delayed and exceeded C-peptide and insulin response to the oral glucose load was determined with deteriorating glucose tolerance. Glucose values did not drop to fasting values at the 180 minute determination in cases of impaired oral glucose tolerance.     

Diabetes mellitus associated with cystic fibrosis

The prevalence of overt diabetes mellitus and carbohydrate intolerance was studied in 448 patients with cystic fibrosis (CF). Insulin-dependent diabetes (IDDM) developed in 7.6% of patients (13 male and 21 female). Survival was significantly lower (P less than 0.01) in the IDDM-CF group, with fewer than 25% surviving to age 30 years, whereas nearly 60% of the nondiabetic CF population reached this age. A significant deterioration in CF clinical status, based on NIH score, became apparent 2 years before onset of overt IDDM (P less than 0.05 at 2 years prior, P less than 0.01 at IDDM diagnosis). Total glycosylated hemoglobin (HbA1) was significantly (P less than 0.001) higher for the total CF population (7.3% +/- 1.2%) than for the general non-CF population (6.5% +/- 0.7%), and in the IDDM-CF group (P less than 0.05) compared with normoglycemic CF control patients. Female patients had a higher mean HbA1 after 12 years of age than their male counterparts did (P less than 0.02). HBA1 did not predict the development of IDDM, but there was a weak inverse relationship between HbA1 and both NIH clinical score (r = -0.41, P less than 0.02) and standard pulmonary function tests (forced vital capacity, r = -0.25, P less than 0.01) in the general CF population. Therefore, impaired carbohydrate tolerance in CF is associated with progressive clinical deterioration.     

Preservation of somatostatin secretion in cystic fibrosis patients with diabetes.

Immunohistochemical studies of pancreatic tissue from patients with cystic fibrosis associated with diabetes mellitus (CFDM) show increased numbers of somatostatin secreting delta cells. To look for a possible functional correlate to this finding basal and arginine stimulated plasma somatostatin and serum C peptide concentrations in eight insulin treated patients with cystic fibrosis and eight normal male controls were measured. Mean basal somatostatin concentrations were not different in the two groups. Mean peak somatostatin concentrations were significantly higher in the group with CFDM: 11.60 pmol/l v 7.14 pmol/l in controls. Mean peak C peptide concentrations were significantly lower in the group with cystic fibrosis: 0.89 nmol/l v 4.27 nmol/l in controls. This observation provides a physiological correlate to the pathological finding of increased somatostatin content in pancreatic tissue from patients with CFDM. Selective preservation of somatostatin secretion in patients with cystic fibrosis may further complicate pancreatic endocrine insufficiencies through paracrine inhibition of insulin and glucagon secretion.     

Night blindness and conjunctival xerosis caused by vitamin A deficiency in patients with cystic fibrosis.

Forty three patients with cystic fibrosis, aged 8-44 years (median 16 years), were examined for evidence of vitamin A deficiency. Eight patients had abnormal dark adaptation tests and three had conjunctival xerosis. Serum vitamin A and retinol binding protein concentrations were significantly lower in the affected patients who were also more likely to have abnormal liver function tests. Five patients were treated with 100,000-200,000 IU water miscible vitamin A orally and their daily vitamin supplements were increased to maintain normal concentrations. In four patients dark adaptation tests were repeated. Three were normal, but one patient required three further doses of water miscible vitamin A and a daily supplement of 12,000 IU vitamin A before her dark adaptation threshold returned to normal. Adolescents with cystic fibrosis are liable to develop night blindness and conjunctival xerosis, particularly if they have liver disease or fail to take daily vitamin supplements.     

Preservation of somatostatin secretion in cystic fibrosis patients with diabetes

Immunohistochemical studies of pancreatic tissue from patients with cystic fibrosis associated with diabetes mellitus (CFDM) show increased numbers of somatostatin secreting delta cells. To look for a possible functional correlate to this finding basal and arginine stimulated plasma somatostatin and serum C peptide concentrations in eight insulin treated patients with cystic fibrosis and eight normal male controls were measured. Mean basal somatostatin concentrations were not different in the two groups. Mean peak somatostatin concentrations were significantly higher in the group with CFDM: 11.60 pmol/l v 7.14 pmol/l in controls. Mean peak C peptide concentrations were significantly lower in the group with cystic fibrosis: 0.89 nmol/l v 4.27 nmol/l in controls. This observation provides a physiological correlate to the pathological finding of increased somatostatin content in pancreatic tissue from patients with CFDM. Selective preservation of somatostatin secretion in patients with cystic fibrosis may further complicate pancreatic endocrine insufficiencies through paracrine inhibition of insulin and glucagon secretion.