Impaired glucose-induced glucagon suppression after partial pancreatectomy

Glucose metabolism after distal pancreatectomy - deterioration of beta cell function becomes noticeable at an early stage: a retrospective cohort study

BACKGROUND

Distal pancreatectomy (DP) can worsen pancreatic endocrine function. Effects on glucose metabolism and underlying mechanisms after DP remains a topic of significant interest and not yet fully understood. This study aimed to examine the impact of DP on blood glucose homeostasis with a particular focus on metabolic outcomes and development of postoperative diabetes.

METHODS

Considered were all patients who underwent DP between 01/2010 and 09/2021 and participated simultaneously in extended blood glucose monitoring with a 12 months follow-up. Blood samples were analyzed for markers of pancreatic endocrine function both fasting and after an oral glucose tolerance test preoperatively and 3 and 12 months after DP.

RESULTS

Included patients (n = 69) were preoperatively categorized into three groups according to American Diabetes Association (ADA) criteria: 17 patients (24.6%) were normoglycemic (NG), 22 (31.9%) had prediabetes (impaired fasting glucose / impaired glucose tolerance - IFG/IGT) and 30 (43.5%) had diabetes mellitus (DM). In the NG subgroup, beta-cell function (HOMA2%B - updated homeostasis model assessment) significantly decreased from 117.4% (101.1-135%) to 66.9% (49.7-102.1%) at 12 months postoperatively (p < 0.05). Insulin sensitivity (HOMA2%S) significantly increased from 48.2% (33.4-66.9%) to 63.5% (49.8-86%) at 12 months postoperatively (p < 0.05). In the IFG/IGT subgroup, there was a non-significant trend of decreased HOMA2%B and increased HOMA2%S postoperatively. Postoperatively, 11.8% of NG patients and 60% of prediabetic patients developed DM.

CONCLUSION

DP already leads to significant changes in glucose metabolism within a 12 month follow-up period. Patients with preoperative prediabetes are particularly at high risk of developing postoperative DM. Therefore, the indication for DP should be critically evaluated, especially in cases with a relative indication for surgery. If possible parenchymal sparing surgical options should be contemplated.

TRIAL REGISTRATION

Not applicable.

In humans increase in intrapancreatic adipose tissue predicts beta-cell dedifferentiation score before diabetes onset: A pilot study

BACKGROUND

The role of intrapancreatic fat (WAT) in the development of T2D remains debated. In T2D, β-cell dedifferentiation is one of the mechanisms responsible for β-cell failure but its role in prediabetes is unknown. We aimed to investigate the relation between WAT and β-cell dedifferentiation prior to diabetes onset.

METHODS

We evaluated pancreatic samples from patients without history of diabetes, who had previously undergone an oral glucose tolerance test and hyperglycemic clamp. Subjects were divided into 3 glucose tolerance groups: normal (NGT), altered (IGT) or newly diagnosed diabetes (nDM). Dedifferentiation and WAT% were morphologically assessed.

RESULTS

WAT was higher in nDM patients compared to NGT and IGT (WAT nDM 43.79 ± 20.83 %, IGT 10.67 ± 8.5 %, NGT 4.43 ± 4.37 %). We observed a progressive increase in dedifferentiation score, in parallel with worsening glucose tolerance (from NGT to IGT to nDM; 4.8 ± 3.8; 32.37 ± 7.4; 40.38 ± 19 respectively). A strong linear regression established that WAT could statistically significantly predict dedifferentiated β-cells (R = 0.86, p = 0.005), and that the predicted increase in dedifferentiated β-cells was 1.25 points for every extra one-point change in WAT. Interestingly, the WAT and dedifferentiation score variable pair were significantly related to 1-hour post-load glycemia.

CONCLUSIONS

The accumulation of WAT might be responsible for dedifferentiation, making it a potential new target to curb diabetes onset.

Lysophosphatidylinositols Are Upregulated After Human β-Cell Loss and Potentiate Insulin Release

In this study, we identified new lipid species associated with the loss of pancreatic β-cells triggering diabetes. We performed lipidomics measurements on serum from prediabetic mice lacking β-cell prohibitin-2 (a model of monogenic diabetes) patients without previous history of diabetes but scheduled for pancreaticoduodenectomy resulting in the acute reduction of their β-cell mass (∼50%), and patients with type 2 diabetes (T2D). We found lysophosphatidylinositols (lysoPIs) were the main circulating lipid species altered in prediabetic mice. The changes were confirmed in the patients with acute reduction of their β-cell mass and in those with T2D. Increased lysoPIs significantly correlated with HbA1c (reflecting glycemic control), fasting glycemia, and disposition index, and did not correlate with insulin resistance or obesity in human patients with T2D. INS-1E β-cells as well as pancreatic islets isolated from nondiabetic mice and human donors exposed to exogenous lysoPIs showed potentiated glucose-stimulated and basal insulin secretion. Finally, addition of exogenous lysoPIs partially rescued impaired glucose-stimulated insulin secretion in islets from mice and humans in the diabetic state. Overall, lysoPIs appear to be lipid species upregulated in the prediabetic stage associated with the loss of β-cells and that support the secretory function of the remaining β-cells.

ARTICLE HIGHLIGHTS

Circulating lysophosphatidylinositols (lysoPIs) are increased in situations associated with β-cell loss in mice and humans such as (pre-)diabetes, and hemipancreatectomy. Pancreatic islets isolated from nondiabetic mice and human donors, as well as INS-1E β-cells, exposed to exogenous lysoPIs exhibited potentiated glucose-stimulated and basal insulin secretion. Addition of exogenous lysoPIs partially rescued impaired glucose-stimulated insulin secretion in islets from mice and humans in the diabetic state. LysoPIs appear as lipid species being upregulated already in the prediabetic stage associated with the loss of β-cells and supporting the function of the remaining β-cells.

Circulating 1,5-Anhydroglucitol as a Biomarker of ß-cell Mass Independent of a Diabetes Phenotype in Human Subjects

CONTEXT

During an asymptomatic prediabetic state, the functional ß-cell mass decreases to a critical threshold, triggering diabetes and related symptoms. To date, there are no reliable readouts able to capture in vivo a potential drop of the ß-cell mass.

OBJECTIVE

Beside its use as a short-term marker of glycemic control, the deoxyhexose 1,5-anhydroglucitol was identified in rodents as a circulating biomarker of the functional ß-cell mass already in the asymptomatic prediabetic stage. The present study investigated the putative corresponding relevance of circulating 1,5-anhydroglucitol in different human cohorts.

METHODS

We analyzed clinical and blood parameters in patients with established type 2 diabetes and subjects considered at high risk of developing diabetes, as well as patients with no history of diabetes scheduled for pancreaticoduodenectomy.

RESULTS

Circulating 1,5-anhydroglucitol was reduced in type 2 diabetic patients, negatively correlating with fasting plasma glucose (P < 0.0001) and hemoglobin A1c (P < 0.0001). In healthy subjects, 1,5-AG levels positively correlated with body mass index (P = 0.004) and Homeostatic Model Assessment of Insulin Resistance %S (P < 0.03) and was particularly high in nondiabetic obese individuals, potentially accounting for compensatory ß-cell expansion. Patients with no history of diabetes undergoing pancreaticoduodenectomy exhibited a 50% reduction of circulating 1,5-anhydroglucitol levels following surgery leading to an acute loss of their ß-cell mass (P = 0.002), regardless their glucose tolerance status.

CONCLUSION

In summary, plasma concentration of 1,5-anhydroglucitol follows the ß-cell mass and its noninvasive monitoring may alert about the loss of ß cells in subjects at risk for diabetes, an event that cannot be captured by other clinical parameters of glycemic control.

Comprehensive evaluation of patterns of hypoglycemia unawareness (HUA) and glycemic variability (GV) in patients with fibrocalculous pancreatic diabetes (FCPD): A cross-sectional study from South India

Objectives

Hypoglycemia unawareness (HUA) in patients with FCPD is common with an unclear etiology. We evaluated the prevalence, characteristics of HUA, glycemic variability (GV), its possible association with pancreatic glucagon secretion & cardiac autonomic function in patients with FCPD.

Methods

A two-week ambulatory glucose profile (AGP) and cardiac autonomic function test was done in patients with FCPD (n = 60), and categorized into UNAWARE (n = 44) and AWARE (n = 16) groups based on the Hypoglycemia Unawareness Index (HUI) score. Glycaemic variability was assessed from the AGP data using Easy GV 9.0.2 software. A subset of patients from both the groups (n = 11) underwent a mixed-meal challenge test and were compared with healthy individuals (controls; n = 11).

Results

HUA was evidenced in 73% (44/60) of patients with FCPD. Significant hypoglycemia, nocturnal hypoglycemia, duration of hypoglycemia and poor cardiac autonomic functions (p = 0.01) were prominent in the UNAWARE group. The overall GV was greater in the UNAWARE group. In the UNAWARE group, significantly reduced fasting and post prandial glucagon levels negatively correlated with HUI (r = -0.74, p < 0.05) and GV-hypoglycemia indices (p < 0.05) In contrast, significantly higher post prandial glucagon levels in the AWARE group positively correlated with post prandial hyperglycemia (r = 0.61, p < 0.05).

Conclusion

Heterogeneity in patterns of glucagon secretion were significantly associated with HUA and GV. Reduced glucagon levels contribute to greater risks of HUA, nocturnal hypoglycemia and greater GV, while hyperglucagonemia predisposes to postprandial hyperglycemia and hypoglycemia awareness in patients with FCPD.

Evaluating perioperative glycemic status after different types of pancreatic surgeries via continuous glucose monitoring system: a pilot study

BACKGROUND

Perioperative glycemic status after pancreatic surgery has never been described. However, it's essential for optimal perioperative glucose management and understanding the pathogenesis of new-onset diabetes mellitus (NODM) after pancreatectomy. Continuous glucose monitoring (CGM) system provides us a helpful tool for closely monitoring and studying perioperative glucose change. This study tried to describe and compare perioperative glucose level and glycemic variability between different types of pancreatic surgeries via CGM device.

METHODS

This study was designed as a prospective observational study. Eighteen patients were enrolled and were grouped by different types of surgery received: control group (CTRL), pancreaticoduodenectomy (PD), distal pancreatectomy (DP), and total pancreatectomy (TP). CGM devices were implanted and initiated right after the surgery. Mean glucose value (MGV), coefficient of variation (CV), mean of daily difference (MODD), continuous overall net glycemic action (CONGA), and time above range (TAR)/time below range (TBR) was compared between groups to assess glucose level and glycemic variability.

RESULTS

TP showed the highest MGV and CV among all groups (P<0.001), while CTRL showed the lowest (P<0.001). PD and DP had similar MGV and CV lower than TP but higher than CTRL (P<0.001). TP had the highest MODD and CONGA, CTRL had the lowest, but no significant differences were found between groups. TP had the highest TAR (24.29%) and the lowest TBR (1.28%), while the control group showed the opposite. The differences in TAR/TBR between groups were all significant (P<0.05).

CONCLUSIONS

TP had the highest mean glucose level and the greatest glycemic variability. PD and DP had similar results: a higher mean glucose level than control but lower than TP. For glycemic variability, PD and DP seemed to have a near-normal result resembling the control group. CGM is useful for glucose monitoring in the perioperative management of pancreatic surgery.

Investigation of the influence of pancreatic surgery on new-onset and persistent diabetes mellitus

AIM

The management of diabetes mellitus (DM) after pancreatic surgery is a long-standing issue. We aimed to investigate DM concerning pancreatic surgery, including new onset diabetes mellitus (NODM), DM resolution, and the change in insulin excretion before/after pancreatic surgery.

METHODS

We retrospectively investigated three different cohorts (total 403 patients) undergoing pancreatectomy. Of those, 275 patients without preoperative DM were investigated for the risk factors of NODM. Fifty-four patients without preoperative DM of the other cohort were assessed for pre/postoperative 24-hour urinary C-peptide excretion (24-hr CPR). To evaluate the influence of pancreatic surgery on DM treatment in patients with preoperative DM, 74 patients were investigated. In all those patients, the pancreatic volume in pre/postoperative images was assessed to estimate the resected pancreatic volume.

RESULTS

NODM was observed in 60 patients (21%), and a lower ratio of remnant pancreatic volume (RRPV) was the only significant risk factor for NODM. Postoperative 24-hr CPR was significantly associated with two factors, RRPV and preoperative 24-hr CPR. Nine of 74 patients with preoperative DM achieved DM resolution after pancreatic surgery, and the presence of gastrointestinal anastomosis was a significant preferable factor for DM resolution.

CONCLUSIONS

Considering the management of DM after surgery, both predicting the postoperative pancreatic volume and the presence of gastrointestinal reconstruction are significant. We concluded that the combined assessment of the predicted remnant pancreatic volume and the preoperative 24-hr CPR value is useful to predict the postoperative pancreatic function.

Pancreaticoduodenectomy model demonstrates a fundamental role of dysfunctional β cells in predicting diabetes

BACKGROUNDThe appearance of hyperglycemia is due to insulin resistance, functional deficits in the secretion of insulin, and a reduction of β cell mass. There is a long-standing debate as to the relative contribution of these factors to clinically manifesting β cell dysfunction. The aim of this study was to verify the acute effect of one of these factors, the reduction of β cell mass, on the subsequent development of hyperglycemia.METHODSTo pursue this aim, nondiabetic patients, scheduled for identical pancreaticoduodenectomy surgery, underwent oral glucose tolerance tests (OGTT) and hyperglycemic clamp (HC) procedures, followed by arginine stimulation before and after surgery. Based on postsurgery OGTT, subjects were divided into 3 groups depending on glucose tolerance: normal glucose tolerance (post-NGT), impaired glucose tolerance (post-IGT), or having diabetes mellitus (post-DM).RESULTSAt baseline, the 3 groups showed similar fasting glucose and insulin levels; however, examining the various parameters, we found that reduced first-phase insulin secretion, reduced glucose sensitivity, and rate sensitivity were predictors of eventual postsurgery development of IGT and diabetes.CONCLUSIONDespite comparable functional mass and fasting glucose and insulin levels at baseline and the very same 50% mass reduction, only reduced first-phase insulin secretion and glucose sensitivity predicted the appearance of hyperglycemia. These functional alterations could be pivotal to the pathogenesis of type 2 diabetes (T2DM).TRIAL REGISTRATIONClinicalTrials.gov NCT02175459.FUNDINGUniversità Cattolica del Sacro Cuore; Italian Ministry of Education, University and Research; European Foundation for the Study of Diabetes.

Insulinbedarf und Glukosehomöostase bei Menschen nach partieller und totaler Pankreatektomie im Vergleich zu Menschen mit anderen Diabetesformen

Einleitung Pankreasresektionen werden bei schwerwiegenden Pankreaserkrankungen durchgeführt. Bei Komplikationen einer chronischen Pankreatitis, teilweise jedoch auch bei Raumforderungen, kann eine Pankreasteilresektion sinnvoll sein. Eine totale Pankreatektomie führt zum absoluten Insulinmangel und der Notwendigkeit einer Insulintherapie. Bei Teilresektionen (partielle Pankreatektomie) werden weniger gravierende Konsequenzen für den Glukosemetabolismus erwartet. Es ist das Ziel der vorliegenden Arbeit, die Insulinregime nach Pankreatektomie mit denen anderer Diabetesformen zu vergleichen.

Material und Methodik Es wurden Patientencharakteristika und Details der postoperativen Insulintherapie von pankreasoperierten Patienten einer spezialisierten Universitätsklinik für Viszeralchirurgie ausgewertet. Diese Daten wurden mit Kohorten nicht operierter Patienten mit Typ-1-Diabetes (T1DM; absoluter Insulinmangel) bzw. Typ-2-Diabetes (T2DM; Insulinresistenz und relativer Insulinmangel), jeweils unter Insulintherapie, verglichen. Ergänzt wurde diese Datenanalyse durch eine Literaturrecherche zu den Stichworten „pancreatogenic diabetes“, „type 3c diabetes“ und „pancreatectomy diabetes“.

Ergebnisse Daten von 32 (68,8 % Frauenanteil) bzw. 41 (43,9 % Frauenanteil) Patienten nach totaler bzw. partieller Pankreatektomie wurden analysiert. Vor der totalen Pankreatektomie hatten 56,3 % der Patienten einen Diabetes mellitus, postoperativ bestand bei allen Patienten eine Insulinpflichtigkeit. Dabei waren die Insulindosierungen im Vergleich mit Patienten mit T1DM (unter intensivierter Insulintherapie) signifikant niedriger (p < 0,0001). Die Dosierungen von Basal- (48,6 % weniger) und Mahlzeiteninsulin (38,1 % weniger) waren gleichermaßen betroffen. Eine partielle Pankreatektomie führte deutlich seltener zu einem Diabetes mellitus, und eine Insulintherapie war nur bei 26,8 % der Patienten erforderlich.

Diskussion Der basale und prandiale Insulinbedarf nach Pankreatektomie ist niedriger als bei einem T1DM und einem T2DM. Dies sollte bei der Blutzuckereinstellung nach Pankreatektomie berücksichtigt werden.

Endocrine and Metabolic Insights from Pancreatic Surgery

Although it is well established that diabetes can also develop as a result of diseases or maneuvers on the exocrine pancreas, the complex relationship between glucose disorders and underlying pancreatic disease is still debated. There is evidence that several features linked to pancreatic diseases can modify endocrine and metabolic conditions before and after surgery. However, pancreatic surgery provides a rare opportunity to correlate in vivo endocrine and metabolic pathways with ex vivo pancreatic samples, to examine the endocrine and metabolic effects of acute islet removal, and finally to clarify the pathogenesis of diabetes. This approach could therefore represent a unique method to shed light on the molecular mechanisms, predicting factors, and metabolic consequences of insulin resistance, islet plasticity, β cell failure, and type 2 diabetes.

Islet cell dysfunction in patients with chronic pancreatitis

Chronic pancreatitis (CP) is characterized by progressive inflammation and fibrosis of the pancreas that eventually leads to pancreatic exocrine and endocrine insufficiency. Diabetes in the background of CP is very difficult to manage due to high glycemic variability and concomitant malabsorption. Progressive beta cell loss leading to insulin deficiency is the cardinal mechanism underlying diabetes development in CP. Alpha cell dysfunction leading to deranged glucagon secretion has been described in different studies using a variety of stimuli in CP. However, the emerging evidence is varied probably because of dependence on the study procedure, the study population as well as on the stage of the disease. The mechanism behind islet cell dysfunction in CP is multifactorial. The intra-islet alpha and beta cell regulation of each other is often lost. Moreover, secretion of the incretin hormones such as glucagon like peptide-1 and glucose-dependent insulinotropic polypeptide is dysregulated. This significantly contributes to islet cell disturbances. Persistent and progressive inflammation with changes in the function of other cells such as islet delta cells and pancreatic polypeptide cells are also implicated in CP. In addition, the different surgical procedures performed in patients with CP and antihyperglycemic drugs used to treat diabetes associated with CP also affect islet cell function. Hence, different factors such as chronic inflammation, dysregulated incretin axis, surgical interventions and anti-diabetic drugs all affect islet cell function in patients with CP. Newer therapies targeting alpha cell function and beta cell regeneration would be useful in the management of pancreatic diabetes in the near future.

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.

Circadian Etiology of Type 2 Diabetes Mellitus

The epidemic of Type 2 diabetes mellitus necessitates development of novel therapeutic and preventative strategies to attenuate expansion of this debilitating disease. Evidence links the circadian system to various aspects of diabetes pathophysiology and treatment. The aim of this review will be to outline the rationale for therapeutic targeting of the circadian system in the treatment and prevention of Type 2 diabetes mellitus and consequent metabolic comorbidities.

Increased β-Cell Workload Modulates Proinsulin-to-Insulin Ratio in Humans

Increased proinsulin secretion, which characterizes type 2 diabetes and insulin resistance, may be due to an intrinsic, primitive defect in proinsulin processing or be secondary to increased demand on β-cells (hyperinsulinemia secondary to insulin resistance). An alternative way to investigate the relation between relative hyperproinsulinemia and increased secretory demand is to study the dynamic changes in the proinsulin-to-insulin ratio after partial pancreatectomy, a model of acute increased β-cell workload on the remaining pancreas. To pursue this aim, patients without diabetes, scheduled for partial pancreatectomy, underwent 4-h mixed-meal tests and hyperinsulinemic-euglycemic clamps before and after surgery. After acute β-cell mass reduction, no changes were observed in the fasting proinsulin-to-insulin ratio, whereas the fold change in the proinsulin-to-insulin ratio significantly increased over time after the meal. Further, our data demonstrate that whole-body insulin resistance is associated with underlying defects in proinsulin secretion, which become detectable only in the presence of increased insulin secretion demand.

Diabetes associated with pancreatic diseases

PURPOSE OF REVIEW

A relevant number of patients with pancreatic disorders suffer from secondary diabetes. Recent data have shed light on the link between pancreatic damage and subsequent impairments in glucose homeostasis. Furthermore, epidemiological studies provided insights into the relationship between diabetes and the risk of pancreatic carcinoma or pancreatitis. Pancreaticogenic diabetes requires a tailored therapeutic approach taking into account the individual properties of the available glucose-lowering drugs.

RECENT FINDINGS

We review the available literature concerning diabetes in patients with acute or chronic pancreatitis or pancreatic carcinoma. The relationship between the pancreatic damage and alterations in insulin and glucose homeostasis is summarized as well as the effect of diabetes mellitus on the risk of pancreatic cancer and pancreatitis. Caveats in the treatment of pancreaticogenic diabetes with currently available drugs are being discussed.

SUMMARY

Patients with pancreatic diseases should be screened for diabetes by means of an oral glucose tolerance test. There is a close inverse relationship between pancreatic β-cell loss and postchallenge hyperglycemia. The risk of hypoglycemia may be increased in patients with pancreaticogenic diabetes. Newly diagnosed diabetes may be a harbinger of pancreatic cancer. There is increasing evidence suggesting an increased risk for (pancreatic) cancer and pancreatitis in patients with diabetes mellitus. Further studies on the ideal glucose-lowering treatment of patients with pancreaticogenic diabetes will be required.

Diabetes after pancreatic surgery: novel issues

In the developed world, pancreatic surgery is becoming more common, with an increasing number of patients developing diabetes because of either partial or total pancreatectomy, with a significant impact on quality of life and survival. Although these patients are expected to consume increasing health care resources in the near future, many aspects of diabetes after pancreatectomy are still not well defined. The treatment of diabetes in these patients takes advantage of the therapies used in type 1 and 2 diabetes; however, no specific guidelines for its management, both immediately after pancreatic surgery or in the long term, have been developed. In this article, on the basis of both the literature and our clinical experience, we address the open issues and discuss the most appropriate therapeutic options for patients with diabetes after pancreatectomy.

Pancreatic surgery: evolution and current tailored approach

Surgical resection of pancreatic cancer offers the only chance for prolonged survival. Pancretic resections are technically challenging, and are accompanied by a substantial risk for postoperative complications, the most significant complication being a pancreatic fistula. Risk factors for development of pancreatic leakage are now well known, and several prophylactic pharmacological measures, as well as technical interventions have been suggested in prevention of pancreatic fistula. With better postoperative care and improved radiological interventions, most frequently complications can be managed conservatively. This review also attempts to address some of the controversies related to optimal management of the pancreatic remnant after pancreaticoduodenectomy.

Autologous islet transplantation in patients requiring pancreatectomy for neoplasm

Autologous islet cell transplantation is a procedure performed to prevent or reduce the severity of diabetes after pancreatic resection. Autologous islet cell transplantation is being used almost exclusively in patients undergoing pancreatectomy because of painful, chronic pancreatitis, or multiple recurrent episodes of pancreatitis that is not controlled by standard medical and surgical treatments. Here, we discuss the possibility of extending the clinical indications for this treatment on the basis of our experience in patients undergoing pancreatic surgery for both nonmalignant and malignant diseases, including patients undergoing completion pancreatectomy because of anastomosis leakage after pancreaticoduodenectomy and those with pancreatic anastomosis deemed at high risk for failure.

Insulin resistance alters islet morphology in nondiabetic humans

Type 2 diabetes is characterized by poor glucose uptake in metabolic tissues and manifests when insulin secretion fails to cope with worsening insulin resistance. In addition to its effects on skeletal muscle, liver, and adipose tissue metabolism, it is evident that insulin resistance also affects pancreatic β-cells. To directly examine the alterations that occur in islet morphology as part of an adaptive mechanism to insulin resistance, we evaluated pancreas samples obtained during pancreatoduodenectomy from nondiabetic subjects who were insulin-resistant or insulin-sensitive. We also compared insulin sensitivity, insulin secretion, and incretin levels between the two groups. We report an increased islet size and an elevated number of β- and α-cells that resulted in an altered β-cell-to-α-cell area in the insulin- resistant group. Our data in this series of studies suggest that neogenesis from duct cells and transdifferentiation of α-cells are potential contributors to the β-cell compensatory response to insulin resistance in the absence of overt diabetes.

Increased plasma β-hydroxybutyrate levels during the fasting test in patients with endogenous hyperinsulinaemic hypoglycaemia

OBJECTIVE

The objective of the present study was to determine whether a plasma β-hydroxybutyrate (BOHB) level >2700 μmol/l during the 72-h fasting test is sufficient to rule out the diagnosis of endogenous hyperinsulinaemic hypoglycaemia (EHH).

RESEARCH DESIGN AND METHODS

We retrospectively studied BOHB levels in 39 patients with EHH who had undergone a 72-H fasting test to make the diagnosis of EHH, and we compared EHH patients with BOHB levels 2700 MOL/L (group 1), EHH PATIENTS with BOHB levels 2700 MOL/L (group 2) and 59 controls (median glycaemia: 3.2  mmol/l and median BOHB: 6095 μmol/l).

RESULTS

During a 72-h fasting test, nine patients (group 1) had BOHB levels >2700  μmol/l (median 6140 and range 2957-7824) and 30 patients (group 2) had BOHB levels <2700 μmol/l (median 542 and range 0-2607). In group 1, four patients had undergone partial pancreatectomy previously and were evaluated for the recurrence of hypoglycaemia, whereas none of the group 2 patients had been operated. The duration of the fasting test was longer in group 1 than in group 2 (P<0.0001), and at the end of the fasting test, plasma glucose concentrations were not significantly different (P=0.0617), but insulin (P=0.004), C-peptide (P=0.0015) and proinsulin (P=0.0038) levels were significantly lower in group 1 patients than in group 2 patients, suggesting lower insulin secretion and/or impaired glycaemic counter-regulation.

CONCLUSION

During a fasting test, a BOHB level >2700 μmol/l is observed in some EHH patients, suggesting that BOHB levels cannot rule out the recurrence of EHH, in particular, after partial pancreatectomy.

Removal of duodenum elicits GLP-1 secretion

OBJECTIVE

To evaluate the effect of removal of the duodenum on the complex interplay between incretins, insulin, and glucagon in nondiabetic subjects.

RESEARCH DESIGN AND METHODS

For evaluation of hormonal secretion and insulin sensitivity, 10 overweight patients without type 2 diabetes (age 61 ± 19.3 years and BMI 27.9 ± 5.3 kg/m(2)) underwent a mixed-meal test and a hyperinsulinemic-euglycemic clamp before and after pylorus-preserving pancreatoduodenectomy for ampulloma.

RESULTS

All patients experienced a reduction in insulin (P = 0.002), C-peptide (P = 0.0002), and gastric inhibitory peptide (GIP) secretion (P = 0.0004), while both fasting and postprandial glucose levels increased (P = 0.0001); GLP-1 and glucagon responses to the mixed meal increased significantly after surgery (P = 0.02 and 0.031). While changes in GIP levels did not correlate with insulin, glucagon, and glucose levels, the increase in GLP-1 secretion was inversely related to the postsurgery decrease in insulin secretion (R(2) = 0.56; P = 0.012) but not to the increased glucagon secretion, which correlated inversely with the reduction of insulin (R(2) = 0.46; P = 0.03) and C-peptide (R(2) = 0.37; P = 0.04). Given that the remaining pancreas presumably has preserved intraislet anatomy, insulin secretory capacity, and α- and β-cell interplay, our data suggest that the increased glucagon secretion is related to decreased systemic insulin.

CONCLUSIONS

Pylorus-preserving pancreatoduodenectomy was associated with a decrease in GIP and a remarkable increase in GLP-1 levels, which was not translated into increased insulin secretion. Rather, the hypoinsulinemia may have caused an increase in glucagon secretion.

Immediate post-resection diabetes mellitus after pancreaticoduodenectomy: incidence and risk factors

BACKGROUND

New-onset diabetes mellitus after a pancreaticoduodenectomy (PD) remains poorly defined. The aim of this study was to define the incidence and predictive factors of immediate post-resection diabetes mellitus (iPRDM).

METHODS

Retrospective review of patients undergoing PD from January 2004 through to July 2010. Immediate post-resection diabetes mellitus was defined as diabetes requiring pharmacological treatment within 30 days post-operatively. Logistic regression was conducted to identify factors predictive of iPRDM.

RESULTS

Of 778 patients undergoing PD, 214 were excluded owing to pre-operative diabetes (n= 192), declined research authorization (n= 14) or death prior to hospital discharge (n= 8); the remaining 564 patients comprised the study population. iPRDM occurred in 22 patients (4%) who were more likely to be male, have pre-operative glucose intolerance, or an increased creatinine, body mass index (BMI), pre-operative glucose, operative time, tumour size or specimen length compared with patients without iPRDM (P < 0.05). On multivariate analysis, pre-operative impaired glucose intolerance (P < 0.001), pre-operative glucose ≥ 126 (P < 0.001) and specimen length (P= 0.002) were independent predictors of iPRDM. A predictive model using these three factors demonstrated a c-index of 0.842.

DISCUSSION

New-onset, post-resection diabetes occurs in 4% of patients undergoing PD. Factors predictive of iPRDM include pre-operative glucose intolerance, elevated pre-operative glucose and increased specimen length. These data are important for patient education and predicting outcomes after PD.

CTCF mediates effect of insulin on glucagon expression

Pancreatic islet α-cell development and glucagon production are mainly regulated by Pax6 in the homeobox gene families. However, the molecular mechanism fine-tuning the regulation of these events in α-cell still remains unclear. In ocular cells, Pax6 transcription is regulated by CTCF through its binding to specific sites in Pax6 promoter. In this study, CTCF-mediated regulations of islet α-cell development and glucagon production were investigated in both CTCF transgenic mice and α-TC-1-6 cells. Over-expression of CTCF in transgenic mice affected development of pancreatic islets by significantly suppressing α-cell population in both embryonic and adult pancreases. The effect of CTCF on Pax6 gene expression and subsequently, on pro-glucagon production was however, examined in pancreatic islet α-cells. Over-expression and knock-down of CTCF directly affected Pax6 expression. More importantly, the CTCF binding sites upstream from Pax6 p0 promoter were required for regulating p0 promoter activity in islet α-cells. Stimulation of α-cells with insulin resulted in a significant increase in CTCF expression and a decrease in Pax6 expression, and consequently suppressed pro-glucagon expression. In contrast, these insulin-induced effects were blocked by knockdown of CTCF mRNA with specific siRNA in α-cells. Altogether, our results demonstrated for the first time that CTCF functions as a switch-like molecule between the insulin signaling and the regulations of Pax6 and glucagon expression in pancreatic islet α-cells.

Lentivirus shRNA Grb10 targeting the pancreas induces apoptosis and improved glucose tolerance due to decreased plasma glucagon levels

AIMS/HYPOTHESIS

The physiological significance of growth factor receptor-bound protein-10 (GRB10) in the pancreas is unclear. We hypothesised that GRB10 is involved in pancreatic apoptosis, as GRB10 binds with a family of cell-survival-related proteins implicated in apoptosis.

METHODS

Lentiviral vector small hairpin RNA (shRNA) targeting Grb10 was injected in vivo via an intraductal pancreatic route to target pancreatic tissues in adult mice, which were studied 2 weeks post-injection.

RESULTS

Using the TUNEL assay, we demonstrated for the first time that in vivo injection of lentivirus shRNA Grb10 directly into the adult mouse pancreas induced apoptosis in both exocrine and endocrine (alpha and beta) cells. This effect was more pronounced in alpha cells. Levels of the pro-apoptotic protein BCL2-interacting mediator of cell death (BIM) in islets was higher in lentivirus shRNA Grb10 than in lentivirus shRNA scramble mice. In the apoptotic pathway, BIM initiates apoptosis signalling, leading to activation of the caspase cascade. We propose that, when complexed with GRB10, BIM is inactive. On activation by stress signalling or, in the present study, following injection of lentivirus shRNA Grb10 into pancreas, BIM becomes unbound from GRB10 and activates the caspase cascade. Indeed, caspase-3 activity in islets was higher in the experimental than in the control group. Apoptosis induced by shRNA Grb10 resulted in a 34% decrease in fasting plasma glucagon. Mice injected with shRNA Grb10 had improved glucose tolerance despite reduced insulin secretion compared with shRNA scramble control mice.

CONCLUSIONS/INTERPRETATION

GRB10 is critically involved in alpha cell survival and, as a result, plays an important role in regulating basal glucagon secretion and glucose tolerance in adult mice.

Pancreatogenic diabetes after pancreatic resection

The loss of pancreatic parenchyma resulting from pancreatic resection causes an extreme disruption of glucose homeostasis known as pancreatogenic diabetes. This form of glucose intolerance is different from the other forms of diabetes mellitus in that affected individuals suffer frequent episodes of iatrogenic hypoglycemia. The development of sophisticated surgical procedures, improved postoperative care, and the capacity for early diagnosis of disease has prolonged life expectancy after pancreatic resection. For this reason, pancreatogenic diabetes is now attracting attention as the primary factor influencing quality of life in patients who have undergone this procedure. The incidence of new-onset diabetes mellitus after pancreatic resection increases as the follow-up period after surgery becomes longer and is related to the progression of underlying disease, the type of surgery, and the extent of resection. The pathophysiology of pancreatogenic diabetes is related to pancreatic hormone deficiency and the altered responses of the liver and peripheral organs to lower than normal hormone levels. Hyperglycemia occurs when the amount of insulin produced or administered is insufficient because of unsuppressed hepatic glucose production secondary to a deficiency in pancreatic polypeptide. In contrast, patients lapse into hypoglycemia when insulin is barely excessive because of enhanced peripheral insulin sensitivity and glucagon deficiency. Nutritional state, pancreatic exocrine function and intestinal function also affect glycemic control. Insulin replacement is considered to be the main treatment option for insulin dependent pancreatogenic diabetes. Pancreatic polypeptide replacement and islet autotransplantation have potential as new approaches to treating patients with pancreatogenic diabetes after pancreatic resection. and IAP.

Diminished glucagon suppression after β-cell reduction is due to impaired α-cell function rather than an expansion of α-cell mass

Impaired suppression of glucagon levels after oral glucose or meal ingestion is a hallmark of type 2 diabetes. Whether hyperglucagonemia after a β-cell loss results from a functional upregulation of glucagon secretion or an increase in α-cell mass is yet unclear. CD-1 mice were treated with streptozotocin (STZ) or saline. Pancreatic tissue was collected after 14, 21, and 28 days and examined for α- and β-cell mass and turnover. Intraperitoneal (ip) glucose tolerance tests were performed at day 28 as well as after 12 days of subcutaneous insulin treatment, and glucose, insulin, and glucagon levels were determined. STZ treatment led to fasting and post-challenge hyperglycemia (P < 0.001 vs. controls). Insulin levels increased after glucose injection in controls (P < 0.001) but were unchanged in STZ mice (P = 0.36). Intraperitoneal glucose elicited a 63.1 ± 4.1% glucagon suppression in control mice (P < 0.001), whereas the glucagon suppression was absent in STZ mice (P = 0.47). Insulin treatment failed to normalize glucagon levels. There was a significant inverse association between insulin and glucagon levels after ip glucose ingestion (r(2) = 0.99). β-Cell mass was reduced by ∼75% in STZ mice compared with controls (P < 0.001), whereas α-cell mass remained unchanged (P > 0.05). α-Cell apoptosis (TUNEL) and replication (Ki67) were rather infrequently noticed, with no significant differences between the groups. These studies underline the importance of endogenous insulin for the glucose-induced suppression of glucagon secretion and suggest that the insufficient decline in glucagon levels after glucose administration in diabetes is primarily due to a functional loss of intraislet inhibition of α-cell function rather than an expansion of α-cell mass.