Pancreatic enzyme supplementation improves the incretin hormone response and attenuates postprandial glycemia in adolescents with cystic fibrosis: a randomized crossover trial

Early-phase insulin secretion during mixed-meal tolerance testing predicts β-cell function and secretory capacity in cystic fibrosis

Insulin secretion within 30 minutes of nutrient ingestion is reduced in people with cystic fibrosis (PwCF) and pancreatic insufficiency and declines with worsening glucose tolerance. The glucose potentiated arginine (GPA) test is validated for quantifying β-cell secretory capacity as an estimate of functional β-cell mass but requires technical expertise and is burdensome. This study sought to compare insulin secretion during mixed-meal tolerance testing (MMTT) to GPA-derived parameters in PwCF.

Methods

Secondary data analysis of CF-focused prospective studies was performed in PwCF categorized as 1) pancreatic insufficient [PI-CF] or 2) pancreatic sufficient [PS-CF] and in 3) non-CF controls. MMTT: insulin secretory rates (ISR) were derived by parametric deconvolution using 2-compartment model of C-peptide kinetics, and incremental area under the curve (AUC) was calculated for 30, 60 and 180-minutes. GPA: acute insulin (AIR) and C-peptide responses (ACR) were calculated as average post-arginine insulin or C-peptide response minus pre-arginine insulin or C-peptide under fasting (AIRarg and ACRarg), ~230 mg/dL (AIRpot and ACRpot), and ~340 mg/dL (AIRmax and ACRmax) hyperglycemic clamp conditions. Relationships of MMTT to GPA parameters were derived using Pearson's correlation coefficient. Predicted values were generated for MMTT ISR and compared to GPA parameters using Bland Altman analysis to assess degree of concordance.

Results

85 PwCF (45 female; 75 PI-CF and 10 PS-CF) median (range) age 23 (6-56) years with BMI 23 (13-34) kg/m2, HbA1c 5.5 (3.8-10.2)%, and FEV1%-predicted 88 (26-125) and 4 non-CF controls of similar age and BMI were included. ISR AUC30min positively correlated with AIRarg (r=0.55), AIRpot (r=0.62), and AIRmax (r=0.46) and with ACRarg (r=0.59), ACRpot (r=0.60), and ACRmax (r=0.51) (all P<0.001). ISR AUC30min strongly predicted AIRarg (concordance=0.86), AIRpot (concordance=0.89), and AIRmax (concordance=0.76) at lower mean GPA values, but underestimated AIRarg, AIRpot, and AIRmax at higher GPA-defined β-cell secretory capacity. Between test agreement was unaltered by adjustment for study group, OGTT glucose category, and BMI.

Conclusion

Early-phase insulin secretion during MMTT can accurately predict GPA-derived measures of β-cell function and secretory capacity when functional β-cell mass is reduced. These data can inform future multicenter studies requiring reliable, standardized, and technically feasible testing mechanisms to quantify β-cell function and secretory capacity.

Pancreatic enzyme replacement therapy in subjects with exocrine pancreatic insufficiency and diabetes mellitus: a real-life, case-control study

BACKGROUND

Exocrine pancreatic insufficiency (EPI) can be associated with all types of diabetes. Pancreatic enzyme replacement therapy (PERT) has short and long-term benefits in subjects with EPI, but its effects on diabetes control are uncertain. We aimed to study the effects of PERT initiation on glycemic control in subjects with diabetes and EPI from any cause.

METHODS

In this retrospective study, we compared subjects with EPI and diabetes who were prescribed PERT with subjects with diabetes who had a fecal elastase-1 concentration dosage, but did not receive PERT. The primary outcome was the effect of PERT on hypoglycemia frequency and severity. The secondary outcomes were the effects of PERT on gastro-intestinal disorders, HbA1c and body mass index (BMI).

RESULTS

48 subjects were included in each group. Overall, PERT did not have any significant effect on hypoglycemia frequency or severity, but hypoglycemia frequency tended to decrease in subjects with chronic pancreatitis. While 19% of subjects experienced mild hyperglycemia after PERT initiation, we did not report any keto-acidosis or any other severe adverse event. Gastro-intestinal disorders improved in 80% of subjects treated with PERT, versus in 20% of control subjects (p = 0.02). Gastro-intestinal disorders improved in 87% of subjects with recommended dosage of PERT, versus in 50% of subjects with underdosage (NS). HbA1c and BMI evolution did not differ between the groups.

CONCLUSIONS

PERT initiation is safe in subjects with diabetes and EPI. It does not globally decrease hypoglycemia severity of frequency, but is associated with a decrease in gastro-intestinal disorders. Trial registration Retrospectively registered. The database was registered with the Commission Nationale Informatique et Libertés (CNIL), registration number: 2203351v0. The study was approved by the local ethics committee CLEP, registration number: AAA-2023-09047.

ESPEN-ESPGHAN-ECFS guideline on nutrition care for cystic fibrosis

BACKGROUND

Nutritional status is paramount in Cystic Fibrosis (CF) and is directly correlated with morbidity and mortality. The first ESPEN-ESPGHAN-ECFS guidelines on nutrition care for infants, children, and adults with CF were published in 2016. An update to these guidelines is presented.

METHODS

The study was developed by an international multidisciplinary working group in accordance with officially accepted standards. Literature since 2016 was reviewed, PICO questions were discussed and the GRADE system was utilized. Statements were discussed and submitted for on-line voting by the Working Group and by all ESPEN members.

RESULTS

The Working Group updated the nutritional guidelines including assessment and management at all ages. Supplementation of vitamins and pancreatic enzymes remains largely the same. There are expanded chapters on pregnancy, CF-related liver disease, and CF-related diabetes, bone disease, nutritional and mineral supplements, and probiotics. There are new chapters on nutrition with highly effective modulator therapies and nutrition after organ transplantation.

Diabetes of the Exocrine Pancreas: Implications for Pharmacological Management

Post-pancreatitis diabetes mellitus, pancreatic cancer-related diabetes, and cystic fibrosis-related diabetes are often underappreciated. As a result, a substantial proportion of people with these sub-types of diabetes receive antidiabetic medications that may be suboptimal, if not harmful, in the context of their underlying disease of the exocrine pancreas. The present article delineates both classical (biguanides, insulin, sulfonylureas, α-glucosidase inhibitors, thiazolidinediones, and meglitinides) and newer (glucagon-like peptide-1 receptor agonists, amylin analogs, dipeptidyl peptidase-4 inhibitors, sodium-glucose co-transporter-2 inhibitors, D2 receptor agonists, bile acid sequestrants, and dual glucagon-like peptide-1 receptor and glucose-dependent insulinotropic polypeptide receptor co-agonists) therapies and provides recommendations for managing people with diabetes of the exocrine pancreas based on the most up-to-date clinical evidence. Also, several emerging directions (lipid-enriched pathways, Y4 receptor agonism, glucagon-like peptide-1 and glucagon receptor co-agonism) are presented with a view to informing the process of new drug discovery and development.

Distinct hypoglycemic effect of different formulations of a fixed ratio of basal insulin plus glucagon-like peptide-1 receptor agonist in a patient with pancreatic diabetes

Fixed-ratio combination injection therapy (FRC) is a fixed-ratio mixture containing basal insulin and glucagon-like peptide-1 receptor agonist (GLP-1 RA) in a single injection for the treatment of patients with type 2 diabetes. The two types of FRC products contain different concentrations and mixing ratios of basal insulin and GLP-1 RA. Both products demonstrated satisfactory blood glucose control throughout the day, with less hypoglycemia and weight gain. However, few studies have examined the differences in the actions of the two formulations. Herein, we present a case of a 71-year-old man with pancreatic diabetes and significantly impaired intrinsic insulin secretion capacity, who demonstrated a marked difference in glycemic control following treatment with two different FRC formulations. Treatment with IDegLira, an FRC product, demonstrated suboptimal glucose control in the patient. However, after a change in therapy to another FRC product, IGlarLixi, his glucose control markedly improved, even with a decrease in the injection dose. This difference could have been due to lixisenatide, a short-acting GLP-1RA contained in IGlarLixi, which exerts a postprandial hypoglycemic effect irrespective of intrinsic insulin secretion capacity. In conclusion, IGlarLixi has the potential to achieve good fasting and postprandial glucose control with a once-daily injection, even in patients with type 2 diabetes who have a reduced intrinsic insulin secretion capacity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13340-023-00621-5.

Cystic Fibrosis-Related Diabetes Workshop: Research Priorities Spanning Disease Pathophysiology, Diagnosis, and Outcomes

Cystic fibrosis (CF) is a recessive disorder arising from mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein. CFTR is expressed in numerous tissues, with high expression in the airways, small and large intestine, pancreatic and hepatobiliary ducts, and male reproductive tract. CFTR loss in these tissues disrupts regulation of salt, bicarbonate, and water balance across their epithelia, resulting in a systemic disorder with progressive organ dysfunction and damage. Pancreatic exocrine damage ultimately manifests as pancreatic exocrine insufficiency that begins as early as infancy. Pancreatic remodeling accompanies this early damage, during which abnormal glucose tolerance can be observed in toddlers. With increasing age, however, insulin secretion defects progress such that CF-related diabetes (CFRD) occurs in 20% of teens and up to half of adults with CF. The relevance of CFRD is highlighted by its association with increased morbidity, mortality, and patient burden. While clinical research on CFRD has greatly assisted in the care of individuals with CFRD, key knowledge gaps on CFRD pathogenesis remain. Furthermore, the wide use of CFTR modulators to restore CFTR activity is changing the CFRD clinical landscape and the field's understanding of CFRD pathogenesis. For these reasons, the National Institute of Diabetes and Digestive and Kidney Diseases and the Cystic Fibrosis Foundation sponsored a CFRD Scientific Workshop, 23-25 June 2021, to define knowledge gaps and needed research areas. This article describes the findings from this workshop and plots a path for CFRD research that is needed over the next decade.

Cystic Fibrosis-Related Diabetes Workshop: Research Priorities Spanning Disease Pathophysiology, Diagnosis, and Outcomes

Cystic fibrosis (CF) is a recessive disorder arising from mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein. CFTR is expressed in numerous tissues, with high expression in the airways, small and large intestine, pancreatic and hepatobiliary ducts, and male reproductive tract. CFTR loss in these tissues disrupts regulation of salt, bicarbonate, and water balance across their epithelia, resulting in a systemic disorder with progressive organ dysfunction and damage. Pancreatic exocrine damage ultimately manifests as pancreatic exocrine insufficiency that begins as early as infancy. Pancreatic remodeling accompanies this early damage, during which abnormal glucose tolerance can be observed in toddlers. With increasing age, however, insulin secretion defects progress such that CF-related diabetes (CFRD) occurs in 20% of teens and up to half of adults with CF. The relevance of CFRD is highlighted by its association with increased morbidity, mortality, and patient burden. While clinical research on CFRD has greatly assisted in the care of individuals with CFRD, key knowledge gaps on CFRD pathogenesis remain. Furthermore, the wide use of CFTR modulators to restore CFTR activity is changing the CFRD clinical landscape and the field's understanding of CFRD pathogenesis. For these reasons, the National Institute of Diabetes and Digestive and Kidney Diseases and the Cystic Fibrosis Foundation sponsored a CFRD Scientific Workshop, 23-25 June 2021, to define knowledge gaps and needed research areas. This article describes the findings from this workshop and plots a path for CFRD research that is needed over the next decade.

Screening strategies for glucose tolerance abnormalities and diabetes in people with cystic fibrosis

The increase in life expectancy of patients with cystic fibrosis has come with new comorbidities, particularly diabetes. The gradual development of glucose tolerance abnormalities means that 30 to 40% of adults will be diabetic. Cystic fibrosis-related diabetes is a major challenge in the care of these patients because it is a morbidity and mortality factor at all stages of the disease. Early glucose tolerance abnormalities observed from childhood, before the stage of diabetes, are also associated with a poor pulmonary and nutritional outcome. The long asymptomatic period justifies systematic screening with an annual oral glucose tolerance test from the age of 10 years. However, this strategy does not take into account the new clinical profiles of patients with cystic fibrosis, recent pathophysiological knowledge of glucose tolerance abnormalities, and the emergence of new diagnostic tools in diabetology. In this paper, we summarise the challenges of screening in the current context of new patient profiles - patients who are pregnant, have transplants, or are being treated with fibrosis conductance transmembrane regulator modulators - and put forward an inventory of the various screening methods for cystic fibrosis-related diabetes, including their applications, limitations and practical implications.

Endocrine Complications of Cystic Fibrosis

Endocrine comorbidities have become increasingly important medical considerations as improving cystic fibrosis (CF) care increases life expectancy. Although the underlying pathophysiology of CF-related diabetes remains elusive, the use of novel technologies and therapeutics seeks to improve both CF-related outcomes and quality of life. Improvements in the overall health of those with CF have tempered concerns about pubertal delay and short stature; however, other comorbidities such as hypogonadism and bone disease are increasingly recognized. Following the introduction of highly effective modulator therapies there are many lessons to be learned about their long-term impact on endocrine comorbidities.

Normal and disordered gastric emptying in diabetes: recent insights into (patho)physiology, management and impact on glycaemic control

Gastric emptying is a major determinant of postprandial blood glucose, accounting for ~35% of variance in peak glucose in both healthy individuals and those with type 2 diabetes. Gastric emptying is frequently disordered in individuals with diabetes (both abnormally delayed and accelerated). Delayed gastric emptying, i.e. diabetic gastroparesis, may be linked to upper gastrointestinal symptoms for which current treatment remains suboptimal; pharmacological acceleration of delayed emptying is only weakly associated with symptom improvement. Accordingly, the relationship between symptoms and delayed gastric emptying is not simply 'cause and effect'. In insulin-treated patients, disordered gastric emptying, even when not associated with gastrointestinal symptoms, can cause a mismatch between the onset of insulin action and the availability of absorbed carbohydrate, leading to suboptimal glycaemic control. In patients with type 2 diabetes, interventions that slow gastric emptying, e.g. glucagon-like peptide-1 receptor agonists, reduce postprandial blood glucose. This review focuses on recent insights into the impact of gastric emptying on postprandial blood glucose, effects of diabetes therapy on gastric emptying and the management of disordered gastric emptying in diabetes. In view of the broad relevance of gastric emptying to diabetes management, it is important that future clinical trials evaluating novel therapies that may affect gastric emptying should quantify the latter with an appropriate technique, such as scintigraphy or a stable isotope breath test.

Effects of GLP-1 and GIP on Islet Function in Glucose-Intolerant, Pancreatic-Insufficient Cystic Fibrosis

Impaired insulin and incretin secretion underlie abnormal glucose tolerance (AGT) in pancreatic insufficient cystic fibrosis (PI-CF). Whether the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) can enhance pancreatic islet function in cystic fibrosis (CF) is not known. We studied 32 adults with PI-CF and AGT randomized to receive either GLP-1 (n = 16) or GIP (n = 16) during glucose-potentiated arginine (GPA) testing of islet function on two occasions, with either incretin or placebo infused, in a randomized, double-blind, cross-over fashion. Another four adults with PI-CF and normal glucose tolerance (NGT) and four matched control participants without CF underwent similar assessment with GIP. In PI-CF with AGT, GLP-1 substantially augmented second-phase insulin secretion but without effect on the acute insulin response to GPA or the proinsulin secretory ratio (PISR), while GIP infusion did not enhance second-phase or GPA-induced insulin secretion but increased the PISR. GIP also did not enhance second-phase insulin in PI-CF with NGT but did so markedly in control participants without CF controls. These data indicate that GLP-1, but not GIP, augments glucose-dependent insulin secretion in PI-CF, supporting the likelihood that GLP-1 agonists could have therapeutic benefit in this population. Understanding loss of GIP's insulinotropic action in PI-CF may lead to novel insights into diabetes pathogenesis.

New Concepts in the Pathogenesis of Cystic Fibrosis-Related Diabetes

CONTEXT

Cystic fibrosis-related diabetes (CFRD) is the most common extrapulmonary complication of cystic fibrosis (CF). Approximately 40% of people with CF who are older than 20 years have CFRD. Presence of CFRD is associated with poor health outcomes in people with CF.

OBJECTIVE

This review summarizes current knowledge on pathophysiology of CFRD.

METHODS

A PubMed review of the literature was conducted, with search terms that included CFRD, cystic fibrosis, cystic fibrosis related diabetes, and cystic fibrosis transmembrane conductance regulator (CFTR). Additional sources were identified through manual searches of reference lists. Pathophysiology of CFRD: The pathophysiology underlying development of glucose tolerance abnormalities in CF is complex and not fully understood. β-cell loss and functional impairment of the remaining β-cell function results in progressive insulin insufficiency. Factors that may contribute to development of CFRD include local islet and systemic inflammation, alterations in the incretion hormone axis, varying degrees of insulin resistance and genetic factors related to type 2 diabetes.

CONCLUSION

The prevalence of CFRD is expected to further increase with improving life expectancy of people with CF. Further research is needed to better understand the mechanisms underlying the development of CFRD and the impact of diabetes on clinical outcomes in CF.

Practical aspects of diabetes technology use: Continuous glucose monitors, insulin pumps, and automated insulin delivery systems

There have been tremendous advances in diabetes technology in the last decade. Continuous glucose monitors (CGM), insulin pumps, and automated insulin delivery (AID) systems aim to improve glycemic control while simultaneously decreasing the burden of diabetes management. Although diabetes technologies have been shown to decrease both hypoglycemia and hyperglycemia and to improve health-related quality of life in individuals with type 1 diabetes, the impact of these devices in individuals with cystic fibrosis-related diabetes (CFRD) is less clear. There are unique aspects of CFRD, including the different underlying pathophysiology and unique lived health care experience and comorbidities, that likely affect the use, efficacy, and uptake of diabetes technology in this population. Small studies suggest that CGM is accurate and may be helpful in guiding insulin therapy for individuals with CFRD. Insulin pump use has been linked to improvements in lean body mass and hemoglobin A1c among adults with CFRD. A recent pilot study highlighted the promise of AID systems in this population. This article provides an overview of practical aspects of diabetes technology use and device limitations that clinicians must be aware of in caring for individuals with CF and CFRD. Cost and limited insurance coverage remain significant barriers to wider implementation of diabetes technology use among patients with CFRD. Future studies exploring strategies to improve patient and CF provider education about these devices and studies showing the effectiveness of these technologies on health and patient-reported outcomes may lead to improved insurance coverage and increased rates of uptake and sustained use of these technologies in the CFRD community.

Intestinal Absorption of Lipids Using a Pancreatic Enzyme-Free Nutritional Supplement in Patients with Cystic Fibrosis: A Randomized, Double-Blind, Crossover Pilot Trial

Nutritional supplements for patients with exocrine pancreatic insufficiency (EPI) typically utilize pancreatic enzyme replacement therapy (PERT) which is associated with gastrointestinal side effects. We evaluated serum triglyceride levels in patients with cystic fibrosis following consumption of an enzyme-modified oil oral nutritional supplement (EMO-ONS) versus a standard triacylglycerol-based ONS product (TAG-ONS) used concomitantly with PERT and patient tolerability between the two approaches. Ten subjects with CF and EPI taking PERT were enrolled in a single-center, double-blind, cross-over proof of concept trial. Five subjects randomized to Arm 1 were administered a PERT placebo and EMO-ONS and 5 subjects in Arm 2 were administered TAG-ONS+PERT. After 4 to 14 days, subjects received the opposite ONS. Serum triglyceride levels were measured at baseline and hourly for 6 h. Following the above, subjects were randomly assigned to receive 2 daily servings of EMO-ONS+PERT placebo or TAG-ONS+PERT at home for 7-days, self-reporting gastrointestinal symptoms daily. Mean change in peak serum triglyceride levels were similar for both groups (EMO-ONS = 41.9 ± 46.7 mg/dL vs. TAG-ONS+PERT = 46.4 ± 44.1 mg/L; p = 0.85). There was no difference in mean ratio of the serum triglyceride AUC between the two groups (p = 0.58) or self-reported gastrointestinal tolerance. EMO-based products may provide a PERT-free alternative to traditional ONS products in patients with cystic fibrosis.

Effect of Sitagliptin on Islet Function in Pancreatic Insufficient Cystic Fibrosis With Abnormal Glucose Tolerance

PURPOSE

Impaired incretin secretion may contribute to the defective insulin secretion and abnormal glucose tolerance (AGT) that associate with worse clinical outcomes in pancreatic insufficient cystic fibrosis (PI-CF). The study objective was to test the hypothesis that dipeptidyl peptidase-4 (DPP-4) inhibitor-induced increases in intact incretin hormone [glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP)] concentrations augment insulin secretion and glucagon suppression and lower postprandial glycemia in PI-CF with AGT.

METHODS

26 adults from Children's Hospital of Philadelphia and University of Pennsylvania CF Center with PI-CF and AGT [defined by oral glucose tolerance test glucose (mg/dL): early glucose intolerance (1-h ≥ 155 and 2-h < 140), impaired glucose tolerance (2-h ≥ 140 and < 200 mg/dL), or diabetes (2-h ≥ 200)] were randomized to a 6-month double-blind trial of DPP-4 inhibitor sitagliptin 100 mg daily or matched placebo; 24 completed the trial (n = 12 sitagliptin; n = 12 placebo). Main outcome measures were mixed-meal tolerance test (MMTT) responses for intact GLP-1 and GIP, insulin secretory rates (ISRs), glucagon suppression, and glycemia and glucose-potentiated arginine (GPA) test-derived measures of β- and α-cell function.

RESULTS

Following 6-months of sitagliptin vs placebo, MMTT intact GLP-1 and GIP responses increased (P < 0.001), ISR dynamics improved (P < 0.05), and glucagon suppression was modestly enhanced (P < 0.05) while GPA test responses for glucagon were lower. No improvements in glucose tolerance or β-cell sensitivity to glucose, including for second-phase insulin response, were found.

CONCLUSIONS

In glucose intolerant PI-CF, sitagliptin intervention augmented meal-related incretin responses with improved early insulin secretion and glucagon suppression without affecting postprandial glycemia.

Islet Function in the Pathogenesis of Cystic Fibrosis-Related Diabetes Mellitus

Cystic fibrosis-related diabetes mellitus (CFRD) is the most common non-pulmonary co-morbidity in cystic fibrosis (CF). CF is caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR), which leads to aberrant luminal fluid secretions in organs such as the lungs and pancreas. How dysfunctional CFTR leads to CFRD is still under debate. Both intrinsic effects of dysfunctional CFTR in hormone secreting cells of the islets and effects of exocrine damage have been proposed. In the current review, we discuss these non-mutually exclusive hypotheses with a special focus on how dysfunctional CFTR in endocrine cells may contribute to an altered glucose homeostasis. We outline the proposed role of CFTR in the molecular pathways of β-cell insulin secretion and α-cell glucagon secretion, and touch upon the importance of the exocrine pancreas and intra-pancreatic crosstalk for proper islet function.

Chronic pancreatitis for the clinician. Part 2: Treatment and follow-up. Interdisciplinary Position Paper of the Societat Catalana de Digestologia and the Societat Catalana de Pàncrees

Chronic pancreatitis is associated with impaired quality of life, high incidence of comorbidities, serious complications and mortality. Healthcare costs are exorbitant. Some medical societies have developed guidelines for treatment based on scientific evidence, but the gathered level of evidence for any individual topic is usually low and, therefore, recommendations tend to be vague or weak. In the present position papers on chronic pancreatitis from the Societat Catalana de Digestologia and the Societat Catalana de Pàncrees we aimed at providing defined position statements for the clinician based on updated review of published literature and on multidisciplinary expert agreement. The final goal is to propose the use of common terminology and rational diagnostic/therapeutic circuits based on current knowledge. To this end 51 sections related to chronic pancreatitis were reviewed by 21 specialists from 6 different fields to generate 88 statements altogether. Statements were designed to harmonize concepts or delineate recommendations. Part 2 of these paper series discuss topics on treatment and follow-up. The therapeutic approach should include assessment of etiological factors, clinical manifestations and complications. The complexity of these patients advocates for detailed evaluation in multidisciplinary committees where conservative, endoscopic, interventional radiology or surgical options are weighed. Specialized multidisciplinary units of Pancreatology should be constituted. Indications for surgery are refractory pain, local complications, and suspicion of malignancy. Enzyme replacement therapy is indicated if evidence of exocrine insufficiency or after pancreatic surgery. Response should be evaluated by nutritional parameters and assessment of symptoms. A follow-up program should be planned for every patient with chronic pancreatitis.

A tale of two pancreases: exocrine pathology and endocrine dysfunction

The islets of Langerhans are well embedded within the exocrine pancreas (the latter comprised of ducts and acini), but the nature of interactions between these pancreatic compartments and their role in determining normal islet function and survival are poorly understood. However, these interactions appear to be critical, as when pancreatic exocrine disease occurs, islet function and insulin secretion frequently decline to the point that diabetes ensues, termed pancreatogenic diabetes. The most common forms of pancreatogenic diabetes involve sustained exocrine disease leading to ductal obstruction, acinar inflammation, and fibro-fatty replacement of the exocrine pancreas that predates the development of dysfunction of the endocrine pancreas, as seen in chronic pancreatitis-associated diabetes and cystic fibrosis-related diabetes and, more rarely, MODY type 8. Intriguingly, a form of tumour-induced diabetes has been described that is associated with pancreatic ductal adenocarcinoma. Here, we review the similarities and differences among these forms of pancreatogenic diabetes, with the goal of highlighting the importance of exocrine/ductal homeostasis for the maintenance of pancreatic islet function and survival and to highlight the need for a better understanding of the mechanisms underlying these diverse conditions. Graphical abstract.

Enteroendocrine Hormone Secretion and Metabolic Control: Importance of the Region of the Gut Stimulation

It is now widely appreciated that gastrointestinal function is central to the regulation of metabolic homeostasis. Following meal ingestion, the delivery of nutrients from the stomach into the small intestine (i.e., gastric emptying) is tightly controlled to optimise their subsequent digestion and absorption. The complex interaction of intraluminal nutrients (and other bioactive compounds, such as bile acids) with the small and large intestine induces the release of an array of gastrointestinal hormones from specialised enteroendocrine cells (EECs) distributed in various regions of the gut, which in turn to regulate gastric emptying, appetite and postprandial glucose metabolism. Stimulation of gastrointestinal hormone secretion, therefore, represents a promising strategy for the management of metabolic disorders, particularly obesity and type 2 diabetes mellitus (T2DM). That EECs are distributed distinctively between the proximal and distal gut suggests that the region of the gut exposed to intraluminal stimuli is of major relevance to the secretion profile of gastrointestinal hormones and associated metabolic responses. This review discusses the process of intestinal digestion and absorption and their impacts on the release of gastrointestinal hormones and the regulation of postprandial metabolism, with an emphasis on the differences between the proximal and distal gut, and implications for the management of obesity and T2DM.

Pancreatic enzyme replacement therapy for people with cystic fibrosis

BACKGROUND

Most people with cystic fibrosis (CF) (80% to 90%) need pancreatic enzyme replacement therapy (PERT) to prevent malnutrition. Enzyme preparations need to be taken whenever food is taken, and the dose needs to be adjusted according to the food consumed. A systematic review on the efficacy and safety of PERT is needed to guide clinical practice, as there is variability between centres with respect to assessment of pancreatic function, time of commencing treatment, dose and choice of supplements. This is an updated version of a published review.

OBJECTIVES

To evaluate the efficacy and safety of PERT in children and adults with CF and to compare the efficacy and safety of different formulations of PERT and their appropriateness in different age groups. Also, to compare the effects of PERT in CF according to different diagnostic subgroups (e.g. different ages at introduction of therapy and different categories of pancreatic function).

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Most recent search: 07 November 2019. We also searched an ongoing trials website and the websites of the pharmaceutical companies who manufacture pancreatic enzyme replacements for any additional trials. Most recent search: 26 December 2019.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials in people of any age, with CF and receiving PERT, at any dosage and in any formulation, for a period of not less than four weeks, compared to placebo or other PERT preparations.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trials and extracted outcome data. They also assessed the risk of bias and quality of the evidence (GRADE) of the trials included in the review.

MAIN RESULTS

14 trials were included in the review (641 children and adults with CF), two of these were parallel trials and 12 were cross-over trials. Interventions included different enteric and non-enteric-coated preparations of varying formulations in comparison to each other. The number of participants in each trial varied between 14 and 129. 13 trials were for a duration of four weeks and one trial lasted seven weeks. The majority of the trials had an unclear risk of bias from the randomisation process as the details of this were not given; they also had a high risk of attrition bias and reporting bias. The quality of the evidence ranged from moderate to very low. We mostly could not combine data from the trials as they compared different formulations and the findings from individual trials provided insufficient evidence to determine the size and precision of the effects of different formulations.

AUTHORS' CONCLUSIONS

There is limited evidence of benefit from enteric-coated microspheres when compared to non-enteric coated pancreatic enzyme preparations up to one month. In the only comparison where we could combine any data, the fact that these were cross-over trials is likely to underestimate the level of inconsistency between the results of the trials due to over-inflation of CIs from the individual trials.There is no evidence on the long-term effectiveness and risks associated with PERT. There is also no evidence on the relative dosages of enzymes needed for people with different levels of severity of pancreatic insufficiency, optimum time to start treatment and variations based on differences in meals and meal sizes. There is a need for a properly designed trial that can answer these questions.

Semaglutide in Cystic Fibrosis-Related Diabetes

CONTEXT AND OBJECTIVE

In spite of the evidence that inadequately controlled glycemia is associated with worse clinical outcomes, cystic fibrosis-related diabetes (CFRD) is not well controlled in a majority of patients. The objective of this report is to demonstrate the effect of the addition of semaglutide, a glucagon-like peptide-1 receptor agonist (GLP-1RA), to basal insulin to control glycemia in one such patient.

DESIGN, INTERVENTION, AND THE MAIN OUTCOME MEASURES

The replacement of rapidly acting prandial insulin with semaglutide weekly with continuation of basal insulin. Glycated hemoglobin A1c (HbA1c) was measured and continuous glucose monitoring (CGM) was conducted.

RESULTS

There was a significant improvement in glycemic control, reduction in HbA1c from 9.1% to 6.7% and stable euglycemic pattern on CGM (mean glucose, 142 mg/dL; SD, 51) within 3 months of starting treatment. There was no increase in plasma pancreatic enzyme concentrations.

CONCLUSIONS

Semaglutide at a low dose was able to replace prandial insulin and control glycemia in combination with basal insulin.

Risk factors for development of diabetes mellitus (Type 3c) after partial pancreatectomy: A systematic review

OBJECTIVES

Type 3c diabetes mellitus (T3cDM) occurring post pancreatectomy can be challenging to treat due to the frequent combination of decreased circulating levels of insulin and glucagon and concurrent exocrine insufficiency. Relatively, little is known regarding the risk factors for development of T3cDM post pancreatectomy. Our aim was to review the literature and assess what is known of the risk factors for the development of new-onset DM following partial pancreatic resection and where possible determines the incidence, time of onset and the management approach to hyperglycaemia in this context.

DESIGN

Medline and Embase databases were reviewed using specific keyword criteria. Original manuscripts published in 1990 or later included. Articles with study population <20, lacking information on new-onset DM, follow-up duration or specifically targeting rare procedures/pathology were excluded. The Newcastle Ottawa Quality Assessment form was applied. Results reported according to PRISMA guidelines. Pooled effect size calculated using random effects model.

PATIENTS

Thirty six articles were identified that described a total of 5636 patients undergoing pancreaticoduodenectomy, 3922 patients having distal pancreatectomy and 315 with central pancreatectomy.

RESULTS

The incidence of new-onset DM was significantly different between different types of resection from 9% to 24% after pancreaticoduodenectomy (pooled estimate 16%; 95% CI: 14%-17%), 3%-40% after distal pancreatectomy (pooled estimate 21%; 95% CI: 16%-25%) and 0%-14% after central pancreatectomy (pooled estimate 6%; 95% CI: 3%-9%). Surgical site, higher preoperative HbA1c, fasting plasma glucose and lower remnant pancreatic volume had strongest associations with new-onset DM.

CONCLUSIONS

This systematic review supports that risk of development of T3cDM is associated with type of pancreatic resection, lower remnant pancreatic volume and higher preoperative HbA1c.

Update on pediatric gastroparesis: A review of the published literature and recommendations for future research

BACKGROUND

Due to scarcity of scientific literature on pediatric gastroparesis, there is a need to summarize current evidence and identify areas requiring further research. The aim of this study was to provide an evidence-based review of the available literature on the prevalence, pathogenesis, clinical presentation, diagnosis, treatment, and outcomes of pediatric gastroparesis.

METHODS

A search of the literature was performed using the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines with the following databases: PubMed, EMBASE, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Cochrane Central Register of Controlled Trials, and Web of Science. Two independent reviewers screened abstracts for eligibility.

KEY RESULTS

Our search yielded 1085 original publications, 135 of which met inclusion criteria. Most articles were of retrospective study design. Only 12 randomized controlled trials were identified, all of which were in infants. The prevalence of pediatric gastroparesis is unknown. Gastroparesis may be suspected based on clinical symptoms although these are often non-specific. The 4-hour nuclear scintigraphy scan remains gold standard for diagnosis despite lack of pediatric normative comparison data. Therapeutic approaches include dietary modifications, prokinetic drugs, and postpyloric enteral tube feeds. For refractory cases, intrapyloric botulinum toxin and surgical interventions such as gastric electrical stimulation may be warranted. Most interventions still lack rigorous supportive data.

CONCLUSIONS

Diagnosis and treatment of pediatric gastroparesis are challenging due to paucity of published evidence. Larger and more rigorous clinical trials are necessary to improve outcomes.

Loss of incretin effect contributes to postprandial hyperglycaemia in cystic fibrosis-related diabetes

AIM

To investigate the incretin axis in people with cystic fibrosis.

METHODS

Adults with cystic fibrosis-related diabetes, cystic fibrosis without diabetes, and controls (adults without cystic fibrosis and without diabetes) underwent an oral glucose tolerance test and then a closely matched isoglycaemic i.v. glucose infusion. On each occasion, glucose, insulin, C-peptide, total and active glucagon-like peptide-1 and gastric inhibitory polypeptide responses were recorded and incremental areas under curves were calculated for 60 and 240 min.

RESULTS

Five adults with cystic fibrosis-related diabetes, six with cystic fibrosis without diabetes and six controls, matched for age and BMI, completed the study. Glucose during oral glucose tolerance test closely matched those during isoglycaemic i.v. glucose infusion. The calculated incretin effect was similar in the control group and the cystic fibrosis without diabetes group (28% and 29%, respectively), but was lost in the cystic fibrosis-related diabetes group (cystic fibrosis-related diabetes vs control group: -6% vs 28%; p=0.03). No hyposecretion of glucagon-like peptide-1 or gastric inhibitory polypeptide was observed; conversely, 60-min incremental area under the curve for total glucagon-like peptide-1 was significantly higher in the cystic fibrosis-related diabetes group than in the control group [1070.4 (254.7) vs 694.97 (308.1); p=0.03] CONCLUSIONS: The incretin effect was lost in cystic fibrosis-related diabetes despite adequate secretion of the incretin hormones. These data support the concept that reduced incretin hormone insulinotropic activity contributes significantly to postprandial hyperglycaemia in cystic fibrosis-related diabetes.

The prevalence and impact of low faecal elastase-1 in community-based patients with type 2 diabetes

AIMS

To determine the prevalence of low faecal elastase-1 (FE-1) (≤200 μg/g) in type 2 diabetes (T2DM), and to test the hypothesis that pancreatic enzyme replacement therapy (PERT) would reduce postprandial glycaemia after a high-fat, high-carbohydrate meal in T2DM subjects with low FE-1.

METHODS

Of 109 community-based patients who submitted stool samples, 10 had low FE-1 and 8 were recruited (6 male, 2 female, 67.8 ± 3.0 years). Participants were given a high-fat, high-carbohydrate meal (718 kcal) with either pancrelipase (50,000 units) or placebo in a randomised, double-blind, crossover fashion. The primary outcome was the difference in postprandial glycaemia following PERT vs placebo, as evaluated by the incremental area under the postprandial plasma glucose curve (iAUC). Secondary outcomes included differences in gastric half-emptying time (T50) measured using scintigraphy, and C-peptide iAUC.

RESULTS

The prevalence of low FE-1 in T2DM was 9.2% (95% CI 3.8-14.6%). There was no difference in postprandial glycaemia iAUC (P = 0.38), gastric emptying T50 (P = 0.69) or C-peptide iAUC (P = 0.25) after PERT compared to placebo.

CONCLUSIONS

Decreased FE-1 has a relatively low prevalence in community-based patients with T2DM, and PERT does not reduce postprandial glycaemia in these patients.

CLINICAL TRIAL REGISTRATION NUMBER

ACTRN12617000349347.

Effects of Long-Term Dietary Protein Restriction on Intestinal Morphology, Digestive Enzymes, Gut Hormones, and Colonic Microbiota in Pigs

Simple Summary

In China, a shortage of protein resources is an important limiting factor to the economic benefit of pig production, and the use of protein-restriction diets balanced with amino acids is an effective strategy to save protein resources. However, long-term protein-restriction diets can impair the growth performance, and the reason is still unknown. This study is to investigate the response of gastrointestinal physiology and gut microbiota to the condition of long-term low-protein diet and to try to provide a theoretical foundation for better use of protein resources in swine production. Results showed that presented with moderate protein-restriction diets, pigs are able to adjust their absorption and consumption of nutrients to maintain growth performance; whereas extremely low-protein diets suppress pigs’ appetite, impair intestinal morphology, decrease Lactobacillus and Streptococcus, and reduce energy expenditure. Thus, moderate reduction of dietary protein is more suitable for pig production than extremely low-protein diets supplemented with essential amino acids, and moderate protein-restriction diets can potentially increase protein utilization in pig production.

Abstract

Using protein-restriction diets becomes a potential strategy to save the dietary protein resources. However, the mechanism of low-protein diets influencing pigs’ growth performance is still controversial. This study aimed to investigate the effect of protein-restriction diets on gastrointestinal physiology and gut microbiota in pigs. Eighteen weaned piglets were randomly allocated to three groups with different dietary protein levels. After a 16-week trial, the results showed that feeding a low-protein diet to pigs impaired the epithelial morphology of duodenum and jejunum (p < 0.05) and reduced the concentration of many plasma hormones (p < 0.05), such as ghrelin, somatostatin, glucose-dependent insulin-tropic polypeptide, leptin, and gastrin. The relative abundance of Streptococcus and Lactobacillus in colon and microbiota metabolites was also decreased by extreme protein-restriction diets (p < 0.05). These findings suggested that long-term ingestion of a protein-restricted diet could impair intestinal morphology, suppress gut hormone secretion, and change the microbial community and fermentation metabolites in pigs, while the moderately low-protein diet had a minimal effect on gut function and did not impair growth performance.

Exenatide corrects postprandial hyperglycaemia in young people with cystic fibrosis and impaired glucose tolerance: A randomized crossover trial

Impaired glucose tolerance (IGT) in cystic fibrosis (CF) manifests as postprandial hyperglycaemia. Pancreatic enzyme supplementation reduces the latter; restoring incretin secretion and slowing gastric emptying. We aimed to determine the acute effect of exenatide on postprandial glycaemia in young people with CF and IGT. Six participants with CF and IGT were studied on 2 days, in a double-blind randomized crossover trial. After overnight fasting, they received exenatide 2.5 mcg or placebo (0.9% saline) subcutaneously 15 minutes before a pancake meal labelled with ¹³ C octanoate and pancreatic enzyme replacement. The primary outcomes, area under the curve over 240 minutes (AUC ₂₄₀ ) for blood glucose (P < 0.0001) and peak blood glucose (7.65 mM ± 0.34 [mean ± SE] vs 9.53 mM ± 0.63, P < 0.0001), were markedly lower after exenatide than placebo. AUC₂₄₀ for insulin, C-peptide, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) was also lower after exenatide. Gastric emptying was markedly slower after exenatide, as assessed by time for 10% gastric emptying and peak ¹³ CO₂ excretion. We report for the first time that exenatide corrects postprandial hyperglycaemia in young people with CF and IGT. GLP-1 agonists are a candidate treatment in CF-related diabetes.

Survival in a bad neighborhood: pancreatic islets in cystic fibrosis

In cystic fibrosis (CF), ductal plugging and acinar loss result in rapid decline of exocrine pancreatic function. This destructive process results in remodeled islets, with only a modest reduction in insulin producing β cells. However, β-cell function is profoundly impaired, with decreased insulin release and abnormal glucose tolerance being present even in infants with CF. Ultimately, roughly half of CF subjects develop diabetes (termed CF-related diabetes, CFRD). Importantly, CFRD increases CF morbidity and mortality via worsening catabolism and pulmonary disease. Current accepted treatment options for CFRD are aimed at insulin replacement, thereby improving glycemia as well as preventing nutritional losses and lung decline. CFRD is a unique form of diabetes with a distinct pathophysiology that is as yet incompletely understood. Recent studies highlight emerging areas of interest. First, islet inflammation and lymphocyte infiltration are common even in young children with CF and may contribute to β-cell failure. Second, controversy exists in the literature regarding the presence/importance of β-cell intrinsic functions of CFTR and its direct role in modulating insulin release. Third, loss of the CF transmembrane conductance regulator (CFTR) from pancreatic ductal epithelium, the predominant site of its synthesis, results in paracrine effects that impair insulin release. Finally, the degree of β-cell loss in CFRD does not appear sufficient to explain the deficit in insulin release. Thus, it may be possible to enhance the function of the remaining β cells using strategies such as targeting islet inflammation or ductal CFTR deficiency to effectively treat or even prevent CFRD.

Diabetes of the exocrine pancreas

Diabetes of the exocrine pancreas (DEP) is a form of diabetes that occurs due to pancreatic disease. It is far more common than has been previously considered, with a recent study showing 1.8% of adults with new-onset diabetes should have been classified as DEP. The majority is misdiagnosed as type 2 diabetes mellitus (T2DM). Patients with DEP exhibit varying degrees of exocrine and endocrine dysfunction. Damage to the islet of Langerhans effects the secretion of hormones from the β, α, and pancreatic polypeptide cells; the combination of low insulin, glucagon, and pancreatic polypeptide contributes to rapid fluctuations in glucose levels. This form of "brittle diabetes" may result in the poorer glycemic control observed in patients with DEP, when compared with those with T2DM. Diabetes of the exocrine pancreas has a different natural history to other forms of diabetes; patients are more likely to require early insulin initiation compared with those with T2DM. Therefore, individuals with DEP should be advised about the symptoms of decompensated hyperglycemia, although they are less likely to develop ketoacidosis. Clinicians should screen for DEP in patients with acute or chronic pancreatitis, following pancreatic resection, or with co-existing cystic fibrosis or hemochromatosis. Incident diabetes may herald the onset of pancreatic ductal carcinoma in a small subset of patients. Once identified, patients with DEP can benefit from specific lifestyle advice, pancreatic enzyme replacement therapy, metformin treatment, appropriate insulin dosing, and monitoring. Further research is needed to establish the ideal treatment regimens to provide optimal clinical outcomes for this unique form of diabetes.

Acute Effects of Substitution, and Addition, of Carbohydrates and Fat to Protein on Gastric Emptying, Blood Glucose, Gut Hormones, Appetite, and Energy Intake

Whey protein, when ingested on its own, load-dependently slows gastric emptying and stimulates gut hormone concentrations in healthy young men. The aim of this study was to determine the effects of substitution, and addition, of carbohydrate (dextrose) and fat (olive oil) to whey protein. In randomized, double-blind order, 13 healthy young men (age: 23 ± 1 years, body mass index: 24 ± 1 kg/m²) ingested a control drink (450 mL; ~2 kcal/'control') or iso-volumetric drinks containing protein/carbohydrate/fat: (i) 14 g/28 g/12.4 g (280 kcal/'M_280'), (ii) 70 g/28 g/12.4 g (504kcal/'M_504'), and (iii) 70 g/0 g/0 g (280 kcal/'P_280'), on 4 separate study days. Gastric emptying (n = 11, 3D-ultrasonography), blood glucose, plasma insulin, ghrelin, cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1) concentrations (0⁻180 min), appetite (visual analogue scales), and ad-libitum buffet-meal energy intake (180⁻210 min) were determined. Substitution of protein with carbohydrate and fat was associated with faster gastric emptying (lower 50% emptying time (T50)), reduced suppression of ghrelin, and stimulation of GLP-1 (all P < 0.001); while the addition of carbohydrate and fat to protein did not affect gastric emptying or gut hormone responses significantly. Total energy intake (i.e., drink plus meal) was greater after all caloric drinks than control (P < 0.001). In conclusion, substitution of whey protein with dextrose and olive oil accelerated gastric emptying. Higher protein content of a mixed macronutrient drink increased gut hormone and insulin responses.

Bile acid homeostasis in gastrointestinal and metabolic complications of cystic fibrosis

With the improved treatment of the pulmonary complications of cystic fibrosis (CF), gastrointestinal problems have become more important in the morbidity in CF. A hallmark of the gastrointestinal phenotype of CF, apart from pancreatic insufficiency, is a disruption of bile acid homeostasis. Bile acid homeostasis is important for many gastrointestinal processes including fat absorption, inflammation, microbial composition, as well as regulation of whole body energy metabolism. This review describes the impairment of bile acid homeostasis in CF, its possible consequences for gastrointestinal and metabolic complications and its potential as a target for therapy.

Effect of gender on the acute effects of whey protein ingestion on energy intake, appetite, gastric emptying and gut hormone responses in healthy young adults

BACKGROUND/OBJECTIVES

Protein supplements, usually drinks rich in whey protein, are used widely for weight loss purposes in overweight adults. Information comparing the effects of whey protein on appetite and energy intake in men and women is limited. The objective was to compare the acute effects of whey-protein intake on energy intake, appetite, gastric emptying and gut hormones in healthy young men and women.

SUBJECTS/METHODS

Gastric emptying (3D-ultrasonography), blood glucose and plasma insulin, glucagon, ghrelin, cholecystokinin (CCK), gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) concentrations (0-180 min), appetite (visual analogue scales), and ad libitum energy intake from a buffet meal (180-210 min) were determined after ingestion of 30 g (120 kcal) or 70 g (280 kcal) whey protein, or a flavoured-water control drink (~2 kcal) in 8 healthy young men (25 ± 2 y, 72 ± 3 kg, 23 ± 1 kg/m²) and 8 women (23 ± 1 y, 64 ± 2 kg, 24 ± 0.4 kg/m²).

RESULTS

There was a protein-load effect on gastric emptying, blood glucose, plasma insulin, glucagon, ghrelin, CCK, GIP and GLP-1 concentrations, and perceptions of hunger, desire to eat and prospective food consumption (P < 0.05). Ad libitum energy intake (average decrease of 206 ± 39 kcal (15 ± 2%) for men and of 46 ± 54 kcal (0 ± 26%) for women for the mean of the intakes after the 30 and 70 g whey-protein loads) and hunger were suppressed more by whey-protein ingestion in men than women (P = 0.046). There was no difference in suppression of energy intake between the 30 and 70 g protein loads (P = 0.75, interaction effect P = 0.19). Consequently, total energy intake (protein drink plus buffet meal) increased more compared to control in women than men (P = 0.010). The drinks emptied more slowly, and plasma glucagon, CCK and GLP-1 increased less after the protein drinks, in women than men (P < 0.05).

CONCLUSION

The acute effects of whey protein ingestion on appetite, energy intake, gastric emptying and gut hormone responses are influenced by gender in healthy young adults.

Functional Correlation Between the Pancreas and the Small Intestine in Humans: The First Evaluation Using a Newly Developed Enteroscopy

OBJECTIVES

The aim of this study is to evaluate a functional correlation between the pancreas and the small intestine and the association of this relationship with nutritional status, using magnifying enteroscopy.

METHODS

The subjects were adults aged 20 years or older who underwent upper gastrointestinal endoscopy. An endoscope was inserted into the jejunum, and 10% glucose was sprayed under magnifying observation to evaluate changes in blood flow in the villous capillary network. Mucosal biopsy was performed before and after spraying to evaluate the incretin response in the jejunal mucosa.

RESULTS

A total of 124 patients participated in the study. There was a positive correlation between villous blood flow change and exocrine pancreas function (R = 0.4337, P < 0.0001). Changes of gastric inhibitory polypeptide and glucagon-like peptide messenger RNAs in biopsy samples were positively correlated with endocrine pancreas function in 88 patients without treatment for diabetes (R = 0.4314, P = 0.0012; R = 0.4112, P = 0.0081). In patients with lower villous blood flow change and decreased pancreatic exocrine function, the prognostic nutritional index were significantly lower (P = 0.0098), compared with other patients.

CONCLUSIONS

This study provides the first evidence of a close functional correlation between the pancreas and the small intestine.

Unique challenges of cystic fibrosis-related diabetes

Individuals with cystic fibrosis and pancreatic insufficiency have a gradual decline in insulin secretion over time, which results in an increase in the prevalence of diabetes with age; up to 50% of adults with cystic fibrosis aged over 35 years have diabetes. Cystic fibrosis-related diabetes differs from Type 1 and Type 2 diabetes in several ways; there is a pattern of insulin deficiency with reduced and delayed insulin response to carbohydrates but a sparing of basal insulin that results in glucose abnormalities, which are frequently characterized by normal fasting glucose and postprandial hyperglycaemia. Insulin deficiency and hyperglycaemia, even at levels which do not reach the threshold for a diagnosis of diabetes, have an adverse impact on lung function and clinical status in people with cystic fibrosis. Although the risk of microvascular complications occurs as in other forms of diabetes, the main reason for treatment is to prevent deterioration in lung function and weight loss; treatment may therefore be required at an earlier stage than for other types of diabetes. Treatment is usually with insulin, but management needs to take into account all the other medical issues that arise in cystic fibrosis.

Cystic fibrosis-related diabetes is caused by islet loss and inflammation

Cystic fibrosis-related (CF-related) diabetes (CFRD) is an increasingly common and devastating comorbidity of CF, affecting approximately 35% of adults with CF. However, the underlying causes of CFRD are unclear. Here, we examined cystic fibrosis transmembrane conductance regulator (CFTR) islet expression and whether the CFTR participates in islet endocrine cell function using murine models of β cell CFTR deletion and normal and CF human pancreas and islets. Specific deletion of CFTR from murine β cells did not affect β cell function. In human islets, CFTR mRNA was minimally expressed, and CFTR protein and electrical activity were not detected. Isolated CF/CFRD islets demonstrated appropriate insulin and glucagon secretion, with few changes in key islet-regulatory transcripts. Furthermore, approximately 65% of β cell area was lost in CF donors, compounded by pancreatic remodeling and immune infiltration of the islet. These results indicate that CFRD is caused by β cell loss and intraislet inflammation in the setting of a complex pleiotropic disease and not by intrinsic islet dysfunction from CFTR mutation.

Targeting postprandial glycaemia in children with diabetes: Opportunities and challenges

Postprandial glycaemia makes a substantial contribution to overall glycaemic control in diabetes, particularly in patients whose preprandial glycaemia is relatively well controlled and glycated haemoglobin (HbA1c) only modestly elevated. Our review addresses the determinants of postprandial glycaemia and how it may be targeted therapeutically in children with diabetes. Postprandial glycaemia is influenced by preprandial glycaemia, macronutrients and their absorption, insulin delivery and sensitivity, the action of the enteroendocrine system, and the rate of gastric emptying. Contemporary continuous glucose monitoring systems reveal patterns of post prandial glycaemia and allow management to be guided more precisely. Delays in blood glucose determination, insulin delivery and its absorption remain challenges in the rapidly evolving closed loop continuous subcutaneous insulin and glucagon delivery systems developed for children with type 1 diabetes. Augmentation of the incretin system through nutritional preloads or incretin mimetics targets postprandial glycaemia by slowing gastric emptying as well as insulinotropic and glucagonostatic effects. These treatments are of particular relevance to children with type 2 diabetes. Following the development of targeted therapies in adults, postprandial blood glucose control will now be increasingly targeted in the treatment of diabetes in children.

Targeted intestinal delivery of incretin secretagogues-towards new diabetes and obesity therapies

A new strategy under development for the treatment of type 2 diabetes and obesity is to mimic some of the effects of bariatric surgery by delivering food-related stimuli to the distal gastrointestinal tract where they should enhance the release of gut hormones such as glucagon-like peptide-1 (GLP-1) and peptideYY (PYY). Methods include inhibition of food digestion and absorption in the upper GI tract, or oral delivery of stimuli in capsules or pelleted form to protect them against gastric degradation. A variety of agents have been tested in humans using capsules, microcapsules or pellets, delivering nutrients, bile acids, fatty acids and bitter compounds. This review examines the outcomes of these different approaches and supporting evidence from intestinal perfusion studies.

Effects of Substitution, and Adding of Carbohydrate and Fat to Whey-Protein on Energy Intake, Appetite, Gastric Emptying, Glucose, Insulin, Ghrelin, CCK and GLP-1 in Healthy Older Men-A Randomized Controlled Trial

Protein-rich supplements are used widely for the management of malnutrition in the elderly. We reported previously that the suppression of energy intake by whey protein is less in older than younger adults. The aim was to determine the effects of substitution, and adding of carbohydrate and fat to whey protein, on ad libitum energy intake from a buffet meal (180-210 min), gastric emptying (3D-ultrasonography), plasma gut hormone concentrations (0-180 min) and appetite (visual analogue scales), in healthy older men. In a randomized, double-blind order, 13 older men (75 ± 2 years) ingested drinks (~450 mL) containing: (i) 70 g whey protein (280 kcal; 'P₂₈₀'); (ii) 14 g protein, 28 g carbohydrate, 12.4 g fat (280 kcal; 'M₂₈₀'); (iii) 70 g protein, 28 g carbohydrate, 12.4 g fat (504 kcal; 'M₅₀₄'); or (iv) control (~2 kcal). The caloric drinks, compared to a control, did not suppress appetite or energy intake; there was an increase in total energy intake (drink + meal, p < 0.05), which was increased most by the M₅₀₄-drink. P₂₈₀- and M₅₀₄-drink ingestion were associated with slower a gastric-emptying time (n = 9), lower ghrelin, and higher cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1) than M₂₈₀ (p < 0.05). Glucose and insulin were increased most by the mixed-macronutrient drinks (p < 0.05). In conclusion, energy intake was not suppressed, compared to a control, and particularly whey protein, affected gastric emptying and gut hormone responses.

Effect of Age on Blood Glucose and Plasma Insulin, Glucagon, Ghrelin, CCK, GIP, and GLP-1 Responses to Whey Protein Ingestion

Protein-rich supplements are used widely to prevent and manage undernutrition in older people. We have previously shown that healthy older, compared to younger, adults have less suppression of energy intake by whey protein-although the effects of age on appetite-related gut hormones are largely unknown. The aim of this study was to determine and compare the acute effects of whey protein loads on blood glucose and plasma gut hormone concentrations in older and younger adults. Sixteen healthy older (eight men, eight women; mean ± SEM: age: 72 ± 1 years; body mass index: 25 ± 1 kg/m²) and 16 younger (eight men, eight women; 24 ± 1 years; 23 ± 0.4 kg/m²) adults were studied on three occasions in which they ingested 30 g (120 kcal) or 70 g (280 kcal) whey protein, or a flavored-water control drink (~2 kcal). At regular intervals over 180 min, blood glucose and plasma insulin, glucagon, ghrelin, cholecystokinin (CCK), gastric inhibitory peptide (GIP), and glucagon-like peptide-1 (GLP-1) concentrations were measured. Plasma ghrelin was dose-dependently suppressed and insulin, glucagon, CCK, GIP, and GLP-1 concentrations were dose-dependently increased by the whey protein ingestion, while blood glucose concentrations were comparable during all study days. The stimulation of plasma CCK and GIP concentrations was greater in older than younger adults. In conclusion, orally ingested whey protein resulted in load-dependent gut hormone responses, which were greater for plasma CCK and GIP in older compared to younger adults.

CF-related diabetes: Containing the metabolic miscreant of cystic fibrosis

Cystic fibrosis-related diabetes (CFRD) is associated with both an increase in morbidity and mortality in people with cystic fibrosis (CF). With increased screening and improved life expectancy of people with CF, the prevalence of CFRD is expected to rise further. The underlying pathophysiological mechanisms causing glucose intolerance and diabetes in patients with CF are not well understood but both functional and structural abnormalities in islet cells are likely to have key roles. Insulin therapy improves health outcomes in patients with CF. Future research is needed to better understand the mechanisms underlying the development of CFRD and to develop new screening and treatment strategies to minimize the detrimental impact of CFRD on health outcomes in people with CF.

Evolving Mechanistic Views and Emerging Therapeutic Strategies for Cystic Fibrosis-Related Diabetes

Diabetes is a common and important complication of cystic fibrosis, an autosomal recessive genetic disease due to mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Cystic fibrosis-related diabetes (CFRD) is associated with profound detrimental effects on the disease course and mortality and is expected to increase in prevalence as the survival of patients with cystic fibrosis continues to improve. Despite progress in the functional characterization of CFTR molecular defects, the mechanistic basis of CFRD is not well understood, in part because of the relative inaccessibility of the pancreatic tissue and the limited availability of representative animal models. This review presents a concise overview of the current understanding of CFRD pathogenesis and provides a cutting-edge update on novel findings from human and animal studies. Potential contributions from paracrine mechanisms and β-cell compensatory mechanisms are highlighted, as well as functional β-cell and α-cell defects, incretin defects, exocrine pancreatic insufficiency, and loss of islet cell mass. State-of-the-art and emerging treatment options are explored, including advances in insulin administration, CFTR modulators, cell replacement, gene replacement, and gene editing therapies.

Comparative effects of intraduodenal fat and glucose on the gut-incretin axis in healthy males

BACKGROUND

The interaction of nutrients with the small intestine stimulates the secretion of numerous enteroendocrine hormones that regulate postprandial metabolism. However, differences in gastrointestinal hormonal responses between the macronutrients are incompletely understood. In the present study, we compared blood glucose and plasma hormone concentrations in response to standardised intraduodenal (ID) fat and glucose infusions in healthy humans.

METHODS

In a parallel study design, 16 healthy males who received an intraduodenal fat infusion were compared with 12 healthy males who received intraduodenal glucose, both at a rate of 2kcal/min over 120min. Venous blood was sampled at frequent intervals for measurements of blood glucose, and plasma total and active glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), insulin and glucagon.

RESULTS

Plasma concentrations of the incretin hormones (both total and active GLP-1 and GIP) and glucagon were higher, and plasma insulin and blood glucose concentrations lower, during intraduodenal fat, when compared with intraduodenal glucose, infusion (treatment by time interaction: P<0.001 for each).

CONCLUSIONS

Compared with glucose, intraduodenal fat elicits substantially greater GLP-1, GIP and glucagon secretion, with minimal effects on blood glucose or plasma insulin in healthy humans. These observations are consistent with the concept that fat is a more potent stimulus of the 'gut-incretin' axis than carbohydrate.

Effects of randomized whey-protein loads on energy intake, appetite, gastric emptying, and plasma gut-hormone concentrations in older men and women

Background: Protein- and energy-rich supplements are used widely for the management of malnutrition in the elderly. Information about the effects of protein on energy intake and related gastrointestinal mechanisms and whether these differ between men and women is limited.Objective: We determined the effects of whey protein on energy intake, appetite, gastric emptying, and gut hormones in healthy older men and women.Design: Eight older women and 8 older men [mean ± SEM age: 72 ± 1 y; body mass index (in kg/m²): 25 ± 1] were studied on 3 occasions in which they received protein loads of 30 g (120 kcal) or 70 g (280 kcal) or a flavored water control drink (0 kcal). At regular intervals over 180 min, appetite (visual analog scales), gastric emptying (3-dimensional ultrasonography), and blood glucose and plasma gut-hormone concentrations [insulin, glucagon, ghrelin, cholecystokinin, gastric inhibitory polypeptide (GIP), glucagon-like peptide 1 (GLP-1), and peptide tyrosine tyrosine (PYY)] were measured, and ad libitum energy intake was quantified from a buffet meal (180-210 min; energy intake, appetite, and gastric emptying in the men have been published previously).Results: Energy intake at the buffet meal was ∼80% higher in older men than in older women (P < 0.001). Energy intake was not suppressed by protein compared with the control in men or women (P > 0.05). There was no effect of sex on gastric emptying, appetite, gastrointestinal symptoms, glucose, or gut hormones (P > 0.05). There was a protein load-dependent slowing of gastric emptying, an increase in concentrations of insulin, glucagon, cholecystokinin, GIP, GLP-1, and PYY, and an increase in total energy intake (drink plus meal: 12% increase with 30 g and 32% increase with 70 g; P < 0.001). Energy intake at the buffet meal was inversely related to the stomach volume and area under the curve of hormone concentrations (P < 0.05).Conclusion: In older men and women, whey-protein drinks load-dependently slow gastric emptying and alter gut hormone secretion compared with a control but have no suppressive effect on subsequent ad libitum energy intake. This trial was registered at www.anzctr.org.au as ACTRN12612000941864.

Reduced β-Cell Secretory Capacity in Pancreatic-Insufficient, but Not Pancreatic-Sufficient, Cystic Fibrosis Despite Normal Glucose Tolerance

Patients with pancreatic-insufficient cystic fibrosis (PI-CF) are at increased risk for developing diabetes. We determined β-cell secretory capacity and insulin secretory rates from glucose-potentiated arginine and mixed-meal tolerance tests (MMTTs), respectively, in pancreatic-sufficient cystic fibrosis (PS-CF), PI-CF, and normal control subjects, all with normal glucose tolerance, in order to identify early pathophysiologic defects. Acute islet cell secretory responses were determined under fasting, 230 mg/dL, and 340 mg/dL hyperglycemia clamp conditions. PI-CF subjects had lower acute insulin, C-peptide, and glucagon responses compared with PS-CF and normal control subjects, indicating reduced β-cell secretory capacity and α-cell function. Fasting proinsulin-to-C-peptide and proinsulin secretory ratios during glucose potentiation were higher in PI-CF, suggesting impaired proinsulin processing. In the first 30 min of the MMTT, insulin secretion was lower in PI-CF compared with PS-CF and normal control subjects, and glucagon-like peptide 1 and gastric inhibitory polypeptide were lower compared with PS-CF, and after 180 min, glucose was higher in PI-CF compared with normal control subjects. These findings indicate that despite "normal" glucose tolerance, adolescents and adults with PI-CF have impairments in functional islet mass and associated early-phase insulin secretion, which with decreased incretin responses likely leads to the early development of postprandial hyperglycemia in CF.