The artificial pancreas: two alternative approaches to achieve a fully closed-loop system with optimal glucose control

INTRODUCTION

Diabetes mellitus type 1 is a chronic disease that implies mandatory external insulin delivery. The patients must monitor their blood glucose levels and administer appropriate insulin boluses to keep their blood glucose within the desired range. It requires a lot of time and endeavour, and many patients struggle with suboptimal glucose control despite all their efforts.

MATERIALS AND METHODS

This narrative review combines existing knowledge with new discoveries from animal experiments.

DISCUSSION

In the last decade, artificial pancreas (AP) devices have been developed to improve glucose control and relieve patients of the constant burden of managing their disease. However, a feasible and fully automated AP is yet to be developed. The main challenges preventing the development of a true, subcutaneous (SC) AP system are the slow dynamics of SC glucose sensing and particularly the delay in effect on glucose levels after SC insulin infusions. We have previously published studies on using the intraperitoneal space for an AP; however, we further propose a novel and potentially disruptive way to utilize the vasodilative properties of glucagon in SC AP systems.

CONCLUSION

This narrative review presents two lesser-explored viable solutions for AP systems and discusses the potential for improvement toward a fully automated system: A) using the intraperitoneal approach for more rapid insulin absorption, and B) besides using glucagon to treat and prevent hypoglycemia, also administering micro-boluses of glucagon to increase the local SC blood flow, thereby accelerating SC insulin absorption and SC glucose sensor site dynamics.

Effects of Low-Dose Glucagon on Subcutaneous Insulin Absorption in Pigs

Background

Slow insulin absorption prevents the development of a fully automated artificial pancreas with subcutaneous insulin delivery.

Objective

We have hypothesized that glucagon could be used as a vasodilator to accelerate insulin absorption in a bihormonal subcutaneous artificial pancreas. The present proof-of-concept study is the first study to investigate the pharmacokinetics of insulin after subcutaneous administration of a low dose of glucagon at the site of subcutaneous insulin injection.

Methods

Twelve anesthetized pigs were randomized to receive a subcutaneous injection of 10 IU insulin aspart with either 100 µg glucagon or the equivalent volume of placebo (0.9% saline solution) injected at the same site. Arterial samples were collected for 180 minutes to determine insulin, glucagon, and glucose concentrations.

Results

Glucagon did not influence the insulin concentration Tmax in plasma. The plasma insulin AUC0-∞ was significantly larger after glucagon administration (P < 0.01). The glucagon group had significantly higher glucose concentrations in the first 30 minutes after insulin administration (P < 0.05).

Conclusions

This proof-of-concept study indicates that glucagon may increase the total absorption of a single dose of subcutaneously injected insulin. This is a novel observation. However, we did not observe any reduction in insulin concentration Tmax, as we had hypothesized. Further, glucagon induced a significant, undesirable increase in early blood glucose concentrations.

Vasodilatory effects of glucagon: A possible new approach to enhanced subcutaneous insulin absorption in artificial pancreas devices

Patients with diabetes mellitus type 1 depend on exogenous insulin to keep their blood glucose concentrations within the desired range. Subcutaneous bihormonal artificial pancreas devices that can measure glucose concentrations continuously and autonomously calculate and deliver insulin and glucagon infusions is a promising new treatment option for these patients. The slow absorption rate of insulin from subcutaneous tissue is perhaps the most important factor preventing the development of a fully automated artificial pancreas using subcutaneous insulin delivery. Subcutaneous insulin absorption is influenced by several factors, among which local subcutaneous blood flow is one of the most prominent. We have discovered that micro-doses of glucagon may cause a substantial increase in local subcutaneous blood flow. This paper discusses how the local vasodilative effects of micro-doses of glucagon might be utilised to improve the performance of subcutaneous bihormonal artificial pancreas devices. We map out the early stages of our hypothesis as a disruptive novel approach, where we propose to use glucagon as a vasodilator to accelerate the absorption of meal boluses of insulin, besides using it conventionally to treat hypoglycaemia.

Pharmacokinetics of glucagon after intravenous, intraperitoneal and subcutaneous administration in a pig model

Introduction

There is increasing scientific evidence to substantiate using low‐dose glucagon as a supplement to insulin therapy in artificial pancreata for diabetes mellitus type 1. The delivery of both these hormones intraperitoneally would mimic normal physiology. However, our knowledge of the pharmacological properties of glucagon after intraperitoneal administration is limited. This study compared the pharmacokinetics of glucagon after intraperitoneal, subcutaneous and intravenous administration and the pharmacodynamic effects of glucagon on glucose metabolism after intraperitoneal and subcutaneous administration in a pig model.

Materials and methods

Twelve pigs were included. Glucagon was administered intraperitoneally, subcutaneously and intravenously in a randomised order. Arterial samples were collected every 2–10 min for 150 min to determine plasma glucagon and blood glucose concentrations.

Results

The bioavailability of glucagon was significantly lower after intraperitoneal compared with subcutaneous administration with a median difference (95% confidence interval) of 13% (4–22). The effect of glucagon on glucose metabolism was equal after intraperitoneal and subcutaneous administration.

Conclusions

Intraperitoneal glucagon administration resulted in lower systemic glucagon exposure than subcutaneous administration without loss of efficiency. We interpret this as evidence of a major first‐pass metabolism of glucagon in the liver.

An apathetic child with hallucinations

BACKGROUND

Lysergic acid diethylamide (LSD) is a potent, hallucinogenic substance that distorts the perception, state of consciousness and behaviour of the user. LSD poisonings are rare in children and may be difficult to recognise based on clinical symptoms alone.

CASE PRESENTATION

A young boy was admitted to the hospital because of bizarre behaviour and reduced responsiveness towards his parents. At first, he was agitated. Later he fell silent and became apathetic. He suffered from ataxia and showed signs of visual hallucinations. A conclusive diagnosis of LSD poisoning was made possible through targeted and specific laboratory testing of blood and urine samples. The patient recovered completely without any specific treatment.

INTERPRETATION

We urge doctors who examine paediatric patients with acute and unexplained neuropsychiatric symptoms or abnormal behaviour to consider drug intoxication as a possible differential diagnosis. Blood and urine samples from such patients should be obtained as soon as possible and analysed for a broad spectrum of substances. No antidote exists for LSD. If sedation is required due to convulsions, tachycardia, agitation, or frightening hallucinations, treatment with a benzodiazepine, such as diazepam or midazolam, is recommended.

A patient with maculopapular rash and lichenoid skin damage caused by ponatinib

Tyrosine kinase inhibitors (TKIs) are invaluable for the treatment of patients with chronic myelogenous leukemia. Although TKIs are generally better tolerated than traditional chemotherapy, dermatologic side effects are common and present a significant cause of concern for both patients and physicians. Ponatinib is a third-generation TKI and the only kinase inhibitor effective in patients with certain BCR-ABL1 mutations, including the T315I mutation. However, ponatinib is associated with an increased risk of serious side effects, and severe cutaneous reactions have increasingly been reported. We present a patient who developed a cutaneous lichenoid eruption following the initiation of ponatinib, which resolved after treatment with a topical retinoid. This case demonstrates that cutaneous side effects caused by ponatinib can be managed relatively easily, allowing patients to continue treatment with ponatinib. This is important considerting the limited alternative treatment approaches available for BCR-ABL1 T315I chronic myelogenous leukemia.

Severe nephritis as initial sign of Waldenström's macroglobulinemia

Waldenström's macroglobulinemia (WM), characterized with monoclonal immunoglobulins of type M and lymphoplasmacytic lymphoma, is a rare clonal Bcell disorder. WM usually present as an indolent lymphoma, and renal involvement is, in contrast to multiple myeloma, very rarely seen. We present a patient presenting with severe nephritis and nephrotic range proteinuria of more than 9 g/day as initial manifestations of WM. Furthermore, we discuss diagnostic and therapeutic approaches for this rare manifestation of the disease, in the light of recent research and treatment recommendations.

Should more patients be offered treatment with cannabinoids?

Today, a small but growing number of patients in Norway are prescribed cannabinoids for medical use. Despite the large focus on their potential as medicines, there is limited scientific knowledge about the positive effects, adverse effects, long-term effects and interaction potential of cannabinoids.