Growing body of evidence suggests that intra-pancreatic fat is associated with diabetes but whether distribution of intra-pancreatic fat across the regions of the pancreas has a pathophysiologic role is unknown. The study aimed to investigate the differences in intra-pancreatic fat deposition between the head, body, and tail of the pancreas, as well as the relationship between regional intra-pancreatic fat deposition and diabetes status and insulin traits. A total of 368 adults from the general population underwent magnetic resonance imaging on a 3 T scanner and intra-pancreatic fat was manually quantified in duplicate. Statistical models were adjusted for age, sex, ethnicity, body mass index, and liver fat. Intra-pancreatic fat deposition in the head, body, and tail of the pancreas did not differ significantly in adjusted models, in both the overall cohort and the three subgroups based on diabetes status. HOMA-IR and fasting insulin were significantly positively associated with fat in the tail and body of the pancreas. There was no significant association between regional intra-pancreatic fat and HOMA-β. The association of increased intra-pancreatic fat deposition in the tail and body regions with increased insulin resistance may have an important role in the early identification of patients at risk for developing insulin resistance and diseases that stem from it.

To test whether cerebrospinal fluid (CSF) growth-associated protein 43 (GAP-43) concentration is elevated in Alzheimer’s disease (AD) dementia and its associations with other hallmarks of AD, we examined the CSF GAP-43 measurements of 787 participants (245 cognitively normal (CN), 415 individuals with mild cognitive impairment (MCI) and 127 individuals with AD dementia) from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) study. Associations were investigated between CSF GAP-43 and clinical diagnosis, Aβ/tau/neurodegeneration (AT(N)) status, CSF and blood biomarkers of AD, cognitive measurements and brain neuroimaging findings. CSF GAP-43 levels were increased in patients with AD dementia (mean, 6331.05 pg/ml) compared with the CN (mean, 5001.05 pg/ml) and MCI (mean, 5118.8 pg/ml) (P < 0.001) groups. CSF GAP-43 correlated with CSF phosphorylated tau 181(p-tau) (r = 0.768, P < 0.001), and had high diagnostic accuracy in differentiating tau positive status vs. tau negative status (area under the receiver operating characteristic curve, 0.8606). CSF GAP-43 was particularly elevated among individuals with tau positive status. High CSF GAP-43 was associated with longitudinal deterioration of cognitive scores and brain neuroimaging findings. CSF GAP-43 was associated with a clinical diagnosis of AD dementia and with an individual’s tau status, cognitive measurements and findings from neuroimaging. This study implies that CSF GAP-43 as a biomarker of synaptic dysfunction could predict the disease progression of AD patients.

Both type 2 prediabetes/diabetes (T2DM) and new-onset prediabetes/diabetes after acute pancreatitis (NODAP) are characterized by impaired tissue sensitivity to insulin action. Although the outcomes of NODAP and T2DM are different, it is unknown whether drivers of insulin resistance are different in the two types of diabetes. This study aimed to investigate the associations between abdominal fat phenotypes and indices of insulin sensitivity in non-obese individuals with NODAP, T2DM, and healthy controls. Indices of insulin sensitivity (homeostasis model assessment of insulin sensitivity (HOMA-IS), Raynaud index, triglyceride and glucose (TyG) index, Matsuda index) were calculated in fasting and postprandial states. Fat phenotypes (intra-pancreatic fat, intra-hepatic fat, skeletal muscle fat, visceral fat, and subcutaneous fat) were determined using magnetic resonance imaging and spectroscopy. Linear regression and relative importance analyses were conducted. Age, sex, and glycated hemoglobin A1c were adjusted for. A total of 78 non-obese individuals (26 NODAP, 20 T2DM, and 32 healthy controls) were included. Intra-pancreatic fat was significantly associated with all the indices of insulin sensitivity in the NODAP group, consistently in both the unadjusted and adjusted models. Intra-pancreatic fat was not significantly associated with any index of insulin sensitivity in the T2DM and healthy controls groups. The variance in HOMA-IS was explained the most by intra-pancreatic fat (R2 = 29%) in the NODAP group and by visceral fat (R2 = 21%) in the T2DM group. The variance in the Raynaud index was explained the most by intra-pancreatic fat (R2 = 18%) in the NODAP group and by visceral fat (R2 = 15%) in the T2DM group. The variance in the TyG index was explained the most by visceral fat in both the NODAP group (R2 = 49%) and in the T2DM group (R2 = 25%). The variance in the Matsuda index was explained the most by intra-pancreatic fat (R2 = 48%) in the NODAP group and by visceral fat (R2 = 38%) in the T2DM group. The differing association between intra-pancreatic fat and insulin resistance can be used to differentiate NODAP from T2DM. Insulin resistance in NODAP appears to be predominantly driven by increased intra-pancreatic fat deposition.

Aims/hypothesis The clinical importance of fat deposition in the liver and pancreas is increasingly recognised. However, to what extent deposition of fat in these two depots is affected by intermediate variables is unknown. The aim of this work was to conduct a mediation analysis with a view to uncovering the metabolic traits that underlie the relationship between liver fat and intrapancreatic fat deposition (IPFD) and quantifying their effect. Methods All participants underwent MRI/magnetic resonance spectroscopy on the same 3.0 T scanner to determine liver fat and IPFD. IPFD of all participants was quantified manually by two independent raters in duplicate. A total of 16 metabolic traits (representing markers of glucose metabolism, incretins, lipid panel, liver enzymes, pancreatic hormones and their derivatives) were measured in blood. Mediation analysis was conducted, taking into account age, sex, ethnicity and BMI. Significance of mediation was tested by computing bias-corrected bootstrap CIs with 5000 repetitions. Results A total of 353 individuals were studied. Plasma glucose, HDL-cholesterol and triacylglycerol mediated 6.8%, 17.9% and 24.3%, respectively, of the association between liver fat and IPFD. Total cholesterol, LDL-cholesterol, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, γ-glutamyl transpeptidase, insulin, glucagon, amylin, C-peptide, HbA1c, glucagon-like peptide-1 and gastric inhibitory peptide did not mediate the association between liver fat and IPFD. Conclusions/interpretation At least one-quarter of the association between liver fat and IPFD is mediated by specific blood biomarkers (triacylglycerol, HDL-cholesterol and glucose), after accounting for potential confounding by age, sex, ethnicity and BMI. This unveils the complexity of the association between the two fat depots and presents specific targets for intervention. Graphical abstract

INTRODUCTION: Increased intrapancreatic fat deposition (IPFD) has emerged as a harbinger of pancreatic cancer and chronic pancreatitis. Although it is well recognized that diseases of the exocrine pancreas often lie on a continuum (with acute pancreatitis preceding the development of chronic pancreatitis and/or pancreatic cancer), whether increased IPFD predisposes to acute pancreatitis is unknown. This study aimed to compare fat depositions in the pancreas (as well as the liver and skeletal muscle) between individuals who developed first attack of acute pancreatitis and healthy individuals. METHODS:This was a matched case-control study nested into population-based cohort. MRI on a single 3 T scanner was used to quantify intrapancreatic, liver, and skeletal muscle fat depositions using the same protocols in all study participants. Binary logistic regression with adjustment for body mass index and other possible confounders was performed. RESULTS:Fifty individuals with first attack of nonnecrotizing acute pancreatitis comprised the case group and 100 healthy individuals comprised the control group. A 1% increase in IPFD (but not the other fat depositions) was significantly associated with a more than 30% higher chance of developing first attack of acute pancreatitis, consistently in both the unadjusted (P 5 0.004) and all adjusted models. Furthermore, a 1% increase in IPFD (but not the other fat depositions) was significantly associated with up to a 27% higher chance of developing first attack of acute pancreatitis in individuals with normotriglyceridemia, consistently in both the unadjusted (P 5 0.030) and all adjusted models. DISCUSSION:Increased IPFD may predispose to the development of acute pancreatitis. This opens up opportunities for reducing the burden of acute pancreatitis by means of primary prevention.

<b><i>Introduction:</i></b> Ectopic fat deposition in the pancreas is involved in the pathogenesis of metabolic sequelae following an attack of pancreatitis. However, its relationship with the exocrine pancreas has never been explored in this setting. The aim was to investigate the associations between intra-pancreatic fat deposition (IPFD), pancreas size, and pancreatic enzymes. <b><i>Methods:</i></b> This cross-sectional study recruited individuals with a history of acute pancreatitis and healthy controls. All participants underwent 3T magnetic resonance imaging, from which IPFD, total pancreas volume (TPV), and pancreas diameters (across the head, body, and tail) were measured independently by 2 raters in a blinded fashion. Circulating levels of pancreatic amylase, pancreatic lipase, and chymotrypsin were measured in a fasted state. A series of linear regression analyses was conducted, accounting for possible confounders. <b><i>Results:</i></b> A total of 108 individuals with pancreatitis and 60 healthy controls were studied. There was a statistically significant difference in IPFD (<i>p</i> &#x3c; 0.001), but not in TPV (<i>p</i> = 0.389), between the groups. In the post-pancreatitis group, IPFD was significantly inversely associated with pancreas tail diameter (β = −0.736, <i>p</i> = 0.036 in the most adjusted model). In the control group, IPFD was significantly inversely associated with TPV (β = −3.557, <i>p</i> = 0.026 in the most adjusted model). Levels of pancreatic amylase were significantly directly associated with pancreas tail diameter in the post-pancreatitis group (β = 3.891, <i>p</i> = 0.042 in the most adjusted model), whereas levels of pancreatic lipase were significantly inversely associated with TPV in the control group (β = −10.533, <i>p</i> = 0.024 in the most adjusted model). <b><i>Conclusion:</i></b> Increased IPFD in individuals after an attack of pancreatitis is associated with reduced pancreas tail diameter, which is in turn associated with reduced circulating levels of pancreatic amylase. The relationship between IPFD and the exocrine pancreas warrants further investigations.

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