System approach to modeling of liver glucose metabolism with physiologically interpreted model parameters outgoing from [18F]FDG concentrations measured by PET

Influence of plasma macronutrient levels on hepatic metabolism: role of regulatory networks in homeostasis and disease states

Multilevel regulations by metabolic, signaling and transcription pathways form a complex network that works to provide robust metabolic regulation in the liver. This analysis indicates that dietary perturbations in these networks can lead to insulin resistance.

Evaluation of liver perfusion in diabetic patients using 99mTc-sestamibi

OBJECTIVE

The liver is an important organ for various aspects of glucose metabolism, including glucose uptake, storage, and synthesis. It is a major organ in the metabolic process with perfusion provided by both the portal vein and hepatic artery. In diabetic patients organ perfusion is reduced and this is linked to atherosclerosis, and as a result complications occur. In this study, we aimed to evaluate liver perfusion by scintigraphic methods in diabetic patients.

DESIGN AND PATIENTS

We retrospectively investigated 1,100 myocardial perfusion scintigraphies taken between January 2011 and December 2012 at Canakkale Onsekiz Mart University Medical Faculty Nuclear Medicine Department. A total of 66 patients who were diagnosed with diabetes mellitus and had myocardial perfusion scintigraphies were included in the study. The control subjects included 127 patients without diabetes mellitus who were chosen at random. Patients with chronic liver disease were not included in the study. The values from liver regions of interest (liver-ROI) rates and heart regions of interest (heart-ROI) rates were compared between the patients and controls.

RESULTS

Patients were grouped according to the presence of diabetes. In the diabetes mellitus group, the liver-ROI average was lower (p = 0.66) than in the controls. In the control group, the average liver-ROI/heart-ROI ratios were higher than the ratio in the diabetes mellitus group (p = 0.019). Multivariate variance analysis showed that the diabetes mellitus liver-ROI/heart-ROI ratio was independent of other risk factors (p = 0.003; F: 9.6). Powered by Editorial Manager(®) and ProduXion Manager(®) from Aries Systems Corporation.

CONCLUSIONS

This study shows that liver perfusion in diabetic patients is reduced compared with those without diabetes. Prospective studies with larger patient groups are required.

Brain mass estimation by head circumference and body mass methods in neonatal glycaemic modelling and control

INTRODUCTION

Hyperglycaemia is a common complication of stress and prematurity in extremely low-birth-weight infants. Model-based insulin therapy protocols have the ability to safely improve glycaemic control for this group. Estimating non-insulin-mediated brain glucose uptake by the central nervous system in these models is typically done using population-based body weight models, which may not be ideal.

METHOD

A head circumference-based model that separately treats small-for-gestational-age (SGA) and appropriate-for-gestational-age (AGA) infants is compared to a body weight model in a retrospective analysis of 48 patients with a median birth weight of 750g and median gestational age of 25 weeks. Estimated brain mass, model-based insulin sensitivity (SI) profiles, and projected glycaemic control outcomes are investigated. SGA infants (5) are also analyzed as a separate cohort.

RESULTS

Across the entire cohort, estimated brain mass deviated by a median 10% between models, with a per-patient median difference in SI of 3.5%. For the SGA group, brain mass deviation was 42%, and per-patient SI deviation 13.7%. In virtual trials, 87-93% of recommended insulin rates were equal or slightly reduced (Δ<0.16mU/h) under the head circumference method, while glycaemic control outcomes showed little change.

CONCLUSION

The results suggest that body weight methods are not as accurate as head circumference methods. Head circumference-based estimates may offer improved modelling accuracy and a small reduction in insulin administration, particularly for SGA infants.