A preliminary trial of the programmable implantable medication system for insulin delivery

Direct and indirect control of hepatic glucose production by insulin

There is general agreement that the acute suppression of hepatic glucose production by insulin is mediated by both a direct and an indirect effect on the liver. There is, however, no consensus regarding the relative magnitude of these effects under physiological conditions. Extensive research over the past three decades in humans and animal models has provided discordant results between these two modes of insulin action. Here, we review the field to make the case that physiologically direct hepatic insulin action dominates acute suppression of glucose production, but that there is also a delayed, second order regulation of this process via extrahepatic effects. We further provide our views regarding the timing, dominance, and physiological relevance of these effects and discuss novel concepts regarding insulin regulation of adipose tissue fatty acid metabolism and central nervous system (CNS) signaling to the liver, as regulators of insulin's extrahepatic effects on glucose production.

Long-Term Safety and Efficacy of Programmable Implantable Insulin Delivery Systems

Objectives

Since only short-term studies of continuous intraperitoneal insulin infusion (CIPII) therapy using implantable programmable insulin delivery systems have been performed to show this method of diabetes therapy to be safe and efficacious, we have performed long-term studies to assess its safety and efficacy.

Research design and methods

For 78 patient-years of follow-up, we have longitudinally studied the incidence of diabetic ketoacidosis and severe hypoglycemia in 25 type 1 diabetic patients treated with CIPII. We also compared, cross-sectionally, the long-term safety and efficacy of CIPII to intensive subcutaneous insulin therapy using intermittent injections or continuous subcutaneous insulin infusion. Finally, we examined the relationship between glycated hemoglobin levels and the standard deviation of daily blood glucose excursion.

Results

Cross-sectional analysis revealed similar degrees of metabolic control accompanied by significantly decreased rates of both ketoacidosis (0.013 events/patient/year) and severe hypoglycemia (0.05 events/patient/year) during CIPII compared to intermittent injections and continuous subcutaneous insulin infusion therapy. A four-fold decrease in the rate of severe hypoglycemia was observed during longitudinal comparison of pre- and post-implantation complication rates. A relationship was also shown between decreased levels of mean glycated hemoglobin and the standard deviation of blood glucose excursions during CIPII therapy.

Conclusions

Our data demonstrate that long-term therapy with CIPII is as effective as other methods in achieving near-normal levels of glycated hemoglobin, which in CIPII is associated with a decreased standard deviation of blood glucose excursions. Further, CIPII using implantable programmable insulin delivery systems is the safest method described for intensive insulin therapy in home blood glucose monitoring type 1 diabetic patients.

Finding the right route for insulin delivery - an overview of implantable pump therapy

INTRODUCTION

Implantable pump therapy adopting the intraperitoneal route of insulin delivery has been available for the past three decades. The key rationale for implantable pump therapy is the restoration of the portal-peripheral insulin gradient of the normal physiology. Uptake in clinical practice is limited to specialized centers and selected patient populations. Areas covered: Implantable pump therapy is discussed, including technical aspects, rationale for its use, and glycemic and non-glycemic effects. Target populations, summaries of clinical studies and issues related to implantable pump therapy are highlighted. Limitations of implantable pump therapy and its future outlook in clinical practice are presented. Expert opinion: Although intraperitoneal insulin delivery appears closer to the normal physiology, technical, pharmacological, and costs barriers prevent a wider adoption. Evidence from clinical studies remains scarce and inconclusive. As a consequence, the use of implantable pump therapy will be confined to a small population unless considerable technological progress is made and well-conducted studies can demonstrate glycemic and/or non-glycemic benefits justifying wider application.

Clinical results of an automated artificial pancreas using technosphere inhaled insulin to mimic first-phase insulin secretion

OBJECTIVE

The purpose of this study was to investigate whether or not adding a fixed preprandial dose of inhaled insulin to a fully automated closed loop artificial pancreas would improve the postprandial glucose control without adding an increased risk of hypoglycemia.

RESEARCH DESIGN AND METHODS

Nine subjects with T1DM were recruited for the study. The patients were on closed-loop control for 24 hours starting around 4:30 pm. Mixed meals (~50 g CHO) were given at 6:30 pm and 7:00 am the following day. For the treatment group each meal was preceded by the inhalation of one 10 U dose of Technosphere Insulin (TI). Subcutaneous insulin delivery was controlled by a zone model predictive control algorithm (zone-MPC). At 11:00 am, the patient exercised for 30 ± 5 minutes at 50% of predicted heart rate reserve.

RESULTS

The use of TI resulted in increasing the median percentage time in range (70-180 mg/dl, BG) during the 5-hour postprandial period by 21.6% (81.6% and 60% in the with/without TI cases, respectively, P = .06) and reducing the median postprandial glucose peak by 33 mg/dl (172 mg/dl and 205 mg/dl in the with and without TI cases, respectively, P = .004). The median percentage time in range 80-140 mg/dl during the entire study period was 67.5% as compared to percentage time in range without the use of TI of 55.2% (P = .03).

CONCLUSIONS

Adding preprandial TI (See video supplement) to an automated closed-loop AP system resulted in superior postprandial control as demonstrated by lower postprandial glucose exposure without addition hypoglycemia.

Changes in glucose and fat metabolism in response to the administration of a hepato-preferential insulin analog

Endogenous insulin secretion exposes the liver to three times higher insulin concentrations than the rest of the body. Because subcutaneous insulin delivery eliminates this gradient and is associated with metabolic abnormalities, functionally restoring the physiologic gradient may provide therapeutic benefits. The effects of recombinant human insulin (HI) delivered intraportally or peripherally were compared with an acylated insulin model compound (insulin-327) in dogs. During somatostatin and basal portal vein glucagon infusion, insulin was infused portally (PoHI; 1.8 pmol/kg/min; n = 7) or peripherally (PeHI; 1.8 pmol/kg/min; n = 8) and insulin-327 (Pe327; 7.2 pmol/kg/min; n = 5) was infused peripherally. Euglycemia was maintained by glucose infusion. While the effects on liver glucose metabolism were greatest in the PoHI and Pe327 groups, nonhepatic glucose uptake increased most in the PeHI group. Suppression of lipolysis was greater during PeHI than PoHI and was delayed in Pe327 infusion. Thus small increments in portal vein insulin have major consequences on the liver, with little effect on nonhepatic glucose metabolism, whereas insulin delivered peripherally cannot act on the liver without also affecting nonhepatic tissues. Pe327 functionally restored the physiologic portal-arterial gradient and thereby produced hepato-preferential effects.

Assessment of a new insulin preparation for implanted pumps used in the treatment of type 1 diabetes

BACKGROUND

Implanted insulin pumps using the peritoneal route provide long-term improvement of glucose control compared with subcutaneous insulin therapy in type 1 diabetes (T1D) patients. The stability of insulin preparation is critical for a safe use in implanted pumps. Insuman implantable(®) (400 IU/mL) (Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany), a recombinant human insulin, has been developed as a replacement for Insuplant(®) (Aventis Pharma, Frankfurt am Main, Germany), a semisynthetic insulin, the only one used so far. The aim of the study was to demonstrate the noninferiority of Insuman versus Insuplant, in terms of safety and effectiveness when used in implanted pumps.

SUBJECTS AND METHODS

The patients enrolled, currently treated for T1D by the Medtronic MiniMed (Northridge, CA) implantable pump model 2007 with Insuplant, were randomized into two study arms and received either Insuman or Insuplant for four pump refill cycles. Each pump refill cycle was 40±5 days. The co-primary end points included glycated hemoglobin (HbA1c) change from baseline and pump infusion accuracy.

RESULTS

In total, 169 patients were randomized. Noninferiority of Insuman versus Insuplant was demonstrated both for the HbA1c change from baseline (as a percentage) with intergroup difference of 95% confidence interval (-0.36;+0.11) and for the infusion accuracy assessed by the measured percentage of error at pump refill, as shown by intergroup difference of 95% confidence interval (-5.81; -0.50), in per-protocol populations, although the insulin daily dose was similar. Severe hypoglycemia occurred at least once in 12 versus 11 patients, respectively, and metabolic or technical adverse events were comparable.

CONCLUSIONS

Findings suggest that Insuman can safely and effectively replace Insuplant in implanted pumps.

Current status and future of implantable insulin pumps for the treatment of diabetes

The data from the Diabetes Control and Complications Trial show that control of blood glucose with intensive insulin therapy significantly delays complications of diabetes when compared with conventional therapy consisting of one or two insulin injections per day. However, the subcutaneous intensive insulin therapy, including insulin infusion by external pumps, required to achieve the glycemic goals defined by the Diabetes Control and Complications Trial, led to an increased frequency of severe hypoglycemia. Improvements in parenteral insulin therapy are possible by either modifying subcutaneous insulin kinetics (insulin analogs) or developing better routes of administration. Intraperitoneal insulin infusion offers a more physiologic route of insulin delivery. The ultimate goal for the treatment of diabetes remains the development of a fully automated glucose-controlled device.

Hepatoselectivity and the evolution of insulin

In spite of major developments in insulin production, purification, pharmaceutical formulation and methods of delivery, problems remain both in the day to day management of insulin-treated diabetes and with regard to its long-term complications. The risks of hypoglycaemia and weight gain are major concerns particularly for the patient, and the persistence of microvascular and premature macrovascular complications as the main causes of morbidity and mortality in both type 1 and type 2 diabetes is a constant reminder that our therapeutic and management strategies are inadequate. One clear and striking difference between currently available insulin treatments and normal physiology is the relative difference in exposure to insulin of the liver versus peripheral tissues. Hepatoselective insulin analogues have the potential to restore the normal hepatic to peripheral gradient in insulin action. Here, we discuss the possible therapeutic potential that such analogues may have over currently available insulin preparations. These benefits could include a lower risk of hypoglycaemia, less weight gain and a potential reduction in microvascular and macrovascular complications. We explore the evolution of insulin with hepatoselectivity in mind and possible strategies to create hepatoselective insulins.

Diabetes technology: markers, monitoring, assessment, and control of blood glucose fluctuations in diabetes

People with diabetes face a life-long optimization problem: to maintain strict glycemic control without increasing their risk for hypoglycemia. Since the discovery of insulin in 1921, the external regulation of diabetes by engineering means has became a hallmark of this optimization. Diabetes technology has progressed remarkably over the past 50 years-a progress that includes the development of markers for diabetes control, sophisticated monitoring techniques, mathematical models, assessment procedures, and control algorithms. Continuous glucose monitoring (CGM) was introduced in 1999 and has evolved from means for retroactive review of blood glucose profiles to versatile reliable devices, which monitor the course of glucose fluctuations in real time and provide interactive feedback to the patient. Technology integrating CGM with insulin pumps is now available, opening the field for automated closed-loop control, known as the artificial pancreas. Following a number of in-clinic trials, the quest for a wearable ambulatory artificial pancreas is under way, with a first prototype tested in outpatient setting during the past year. This paper discusses key milestones of diabetes technology development, focusing on the progress in the past 10 years and on the artificial pancreas-still not a cure, but arguably the most promising treatment of diabetes to date.

Complications of continuous intraperitoneal insulin infusion with an implantable pump

AIM: To monitor the course of continuous intraperitoneal insulin infusion (CIPII) and to gain more insight into possible complications.

METHODS: A retrospective, longitudinal observational cohort study in patients with type 1 diabetes mellitus (T1DM) was performed. Only patients with “brittle” T1DM who started CIPII between January 1, 2000 and June 1, 2011, and were treated in the only centre in The Netherlands providing CIPII treatment (Isala clinics, Zwolle) were eligible for inclusion. Outcomes were defined as operation-free period (OFP), rate and type of complications. Subanalyses were made between patients starting CIPII from 2000 to 2007 and from 2007 onwards in order to study possible changes over time in complications and/or OFP. The OFP was calculated as the time from initial implantation to the date of first documented re-operation. If patients had not experienced an operation, their data were recorded at the date of last follow up or death. Kaplan-Meier curves were constructed to visualize the OFP. A (two-sided) P value of less than 0.05 was considered statistically significant.

RESULTS: Fifty-seven patients were treated with CIPII, although one patient was excluded from analyses because of self-induced complications. In the remaining 56 patients, 70 complications occurred during 283 patient years. Catheter occlusion (32.9%), pump dysfunction (17.1%), pain at the pump site (15.7%) and infections (10.0%) were the most frequent complications. This resulted in a median OFP of 4.5 years (95% confidence interval 4.1-4.8 years) without any difference between the time periods. Fifty re-operations were performed because of complications, one per 5.6 patient years, with a decrease in pump dysfunction (P = 0.04) and pump explantations (P = 0.02) after 2007. In total, 9 episodes of ketoacidosis occurred during follow up and there were 69 hospital re-admissions, with a median duration of 6 d. CIPII was ceased in five patients due to recurrent infections (n = 2), pain (n = 1), inadequate glycaemic control (n = 1) or by own choice (n = 1). No CIPII related mortality was reported.

CONCLUSION: The OFP has been stable over the last decade. No CIPII related mortality was reported. A significant decrease in pump dysfunction and explantation was seen after 2007 compared to the period 2000-2007. CIPII remains a safe treatment modality for specific patient groups.

Advances in pump technology: insulin patch pumps, combined pumps and glucose sensors, and implanted pumps

This review discusses the most recent developments in insulin pump technology. The benefits of the insulin pump to patients with type 1 diabetes are recognized both for its metabolic effectiveness and its positive effects on quality of life. The current pumps are reliable, small and light, and are becoming more and more sophisticated. Nevertheless, there remain practical and psychological constraints for the patient. However, recent patch-pump advances should simplify the technical aspects of pump treatment and enhance patient comfort. Another advance combines the insulin pump with a glucose sensor. Such a combination is logical for optimizing pump use and, to that end, developing an automated or 'closed-loop'system that permits the delivery of subcutaneous insulin adjusted according to measured levels of subcutaneous glucose. Finally, implanted insulin pumps have proven their worth not only because of their simple use, but also for their contribution in the artificial pancreas project. Indeed, the prompt response with intraperitoneal administration of insulin makes it of interest for use in a closed-loop system.

Circulating insulin antibodies: influence of continuous subcutaneous or intraperitoneal insulin infusion, and impact on glucose control

The purification of animal insulin preparations and the use of human recombinant insulin have markedly reduced the incidence, but not completely suppressed, the development of anti-insulin antibodies (IAs). Advances in technologies concerning the mode of delivery of insulin, i.e. continuous subcutaneous insulin infusion (CSII), continuous peritoneal insulin infusion (CPII) and more recently inhaled insulin administration, appear to significantly increase circulating levels of immunoglobulin G (IgG) anti-IAs in diabetic patients. However, the increase is usually moderate and mostly transient as compared to previous observations with poorly purified animal insulin preparations. The clinical impact of these circulating anti-IAs remains unclear. Nevertheless, several studies have suggested that antibodies could retard insulin action, leading to a worsening of postprandial hyperglycaemia and/or serve as a carrier, thus leading to unexpected hypoglycaemia. CPII may be associated with more marked and sustained increase in IAs levels, possibly related to the use of an unstable insulin and the formation of immunogenic aggregates of insulin. The possible clinical consequences of these high levels of IAs remain to be evaluated because a low-glucose morning syndrome or severe insulin resistance with ketone bodies production have been reported in some cases. In conclusion, even if CSII and CPII may promote the development of circulating IAs, this increase does not lead to immunological insulin resistance, compared to that previously described with animal non-purified insulin preparations, and seems to have only marginal influence on blood glucose control or complications in most diabetic patients.

Implantable insulin delivery pumps

Implantable insulin delivery pumps are a response to the search for an insulin therapy that would be more physiological, more comfortable and, finally, better adapted to instantaneous insulin needs by their connection to a long term glucose sensor. The last decade has been devoted to their technical finalization and to the acquisition of the clinical knowledge on how to use them, so that these devices can be safe and reliable. The forthcoming availability on the market of the specific insulin formulation they require and the present development of glucose sensors are two favourable conditions for the diffusion of this technology aiming at an improved diabetes treatment. This review summarizes the rationale for the choice of intraperitoneal insulin route, the key-steps in assessing their feasibility and effectiveness in blood glucose control of diabetic patients, and the present development of this technique toward an implantable artificial beta-cell.

A review of the management of implanted medical devices for diabetes: trends and directions

The management of diabetes is progressing rapidly from the use of traditional finger sticks for glucose monitoring and multiple daily injections of insulin to more user-friendly devices and approaches. These advances hold the promise of freeing persons with diabetes from the need for continued daily compliance, thereby improving their quality of life and improving control of their underlying diabetes. An underlying theme to solutions based on percutaneous or fully implanted devices is that the useful lifetime of such devices is often limited by the body's foreign body response. This review briefly outlines general factors associated with point-in-time needle stick approaches to the growing use of short-term percutaneous implants (< or =7 days) to the challenges of more extended devices, both technical and regulatory, faced by developers of these devices.

Optimizing pain control through the use of implantable pumps

Intrathecal therapy represents an effective and well established treatment of nonmalignant as well as malignant pain. Devices available include mechanical constant flow pumps as well as electronic variable flow pumps with patient-controlled bolus release. The latter provide faster dose finding, individual pain control, and good acceptance by patients. New technologies such as membrane pumps and rechargeable devices are expected to be developed to clinical perfection. The available drugs for intrathecal therapy are listed according to the polyanalgesic consensus on intrathecal therapy. The integration of remote patient-controlled analgesia into electronic implantable devices, and the peptide analgesic ziconotide, have significantly improved intrathecal therapy. Complications include infections, catheter ruptures or disconnections, catheter granulomas, and technical dysfunctions. Further possibilities for optimizing intrathecal therapy include development of new drugs, drug side effects, catheter and pump technologies, and surgical techniques.

Insulin delivery route for the artificial pancreas: subcutaneous, intraperitoneal, or intravenous? Pros and cons

Insulin delivery is a crucial component of a closed-loop system aiming at the development of an artificial pancreas. The intravenous route, which has been used in the bedside artificial pancreas model for 30 years, has clear advantages in terms of pharmacokinetics and pharmacodynamics, but cannot be used in any ambulatory system so far. Subcutaneous (SC) insulin infusion benefits from the broad expansion of insulin pump therapy that promoted the availability of constantly improving technology and fast-acting insulin analog use. However, persistent delays of insulin absorption and action, variability and shortterm stability of insulin infusion from SC-inserted catheters generate effectiveness and safety issues in view of an ambulatory, automated, glucose-controlled, artificial beta cell. Intraperitoneal insulin delivery, although still marginally used in diabetes care, may offer an interesting alternative because of its more-physiological plasma insulin profiles and sustained stability and reliability of insulin delivery.

Clinical experience with an implanted closed-loop insulin delivery system

AIM: To report the first clinical experience with a prototype of implanted artificial beta-cell. METHODS: The Long-Term Sensor System® project assessed the feasibility of glucose control by the combined implantation of a pump for peritoneal insulin delivery and a central intravenous glucose sensor, connected physically by a subcutaneous lead and functionally by PID algorithms. It was performed in 10 type 1 diabetic patients from 2000 to 2007. RESULTS: No harmful complication related to implants occurred. Insulin delivery was affected by iterative but reversible pump slowdowns due to insulin precipitation. Glucose measurement by the intravenous sensors correlated well with meter values (r = 0.83-0.93, with a mean absolute deviation of 16.5%) for an average duration of 9 months. Uploading of pump electronics by PID algorithms designed for closed-loop insulin delivery allowed in-patient 48 hourtrials. CONCLUSION: Although the concept of a fully implantable artificial beta-cell has been shown as feasible, improvements in the sensor structure to increase its longevity and decrease sensor delay that affected closed-loop control at meal-times are expected.

Implantable insulin pumps. A position statement about their clinical use

AIM

To review clinical use of implantable insulin pumps and to suggest indications for this therapy.

METHODS

The EVADIAC group performed a review of published reports on implantable insulin pumps for the last 15 years and analyzed its own centralized database. From this update, a position statement on indications of this therapy is drawn.

RESULTS

Published papers mostly report safety and effectiveness data from observational cumulated experiences of 15-350 patient-years. While HbA(1c) reduction does not reach statistical significance in all reported studies, improvement of blood glucose stability and reduction of severe hypoglycaemia appear as constant characteristics of this therapy. When compared to subcutaneous insulin therapy in randomized controlled studies, implantable pumps allow significantly reduced blood glucose fluctuations and improved quality of life in both type 1 and type 2 diabetic patients, and a significant weight decrease in type 2 diabetic patients. While the EVADIAC registry shows the reduced occurrence of pump-pocket complications thanks to preventive measures and a lower incidence of catheter obstructions following improvements of catheter design, underdelivery due to insulin aggregation in pumps remains a recurrent although reversible issue. Determinants of increased anti-insulin antibody production in some patients remain elusive but impact on blood glucose control is limited in most cases.

CONCLUSION

From analyzed data, the EVADIAC group states that implantable pumps can be safely indicated and provide metabolic improvements in type 1 diabetic patients who remain far from targeted HbA(1c) below 7% and/or experience large fluctuations of blood glucose including recurrent severe hypoglycaemia, in spite of intensive follow-up and education when treated by subcutaneous insulin.

Artificial β-cell: clinical experience toward an implantable closed-loop insulin delivery system

AIM

Restoration of long-term normal blood glucose control in diabetic patients supports the elaboration of an artificial beta cell. The possibility of implantation of the three crucial components of such a system (insulin delivery device, glucose sensor and controller) is analyzed.

METHODS

The Long-Term Sensor System project, aiming at a fully implantable artificial beta cell, assessed the feasibility of glucose control by the combined implantation of a pump for peritoneal insulin delivery and a central intravenous glucose sensor close to the right atrium, connected via a subcutaneous lead. It was initiated in 10 Type 1 diabetic patients in our clinic from 2000. Data obtained during this experience are reviewed and confronted to reported closed-loop trials using other approaches.

RESULTS

No significant complication related to prolonged implantation of intravenous sensors occurred and the combined implants were well tolerated. Glucose measurement by the intravenous sensors correlated well with meter values (r=0.83-0.93, with a mean absolute deviation of 16.5%) and accuracy has been sustained for an average duration of 9 months. Uploading of pump electronics by algorithms designed for closed-loop insulin delivery allowed in-patient 48 hour-trials aiming at automated glucose control. Glucose control was similar to that reported by investigations combining subcutaneous sensors to wearable pumps for subcutaneous insulin infusion. The benefits of more physiological insulin kinetics due to intra-peritoneal delivery have been hampered by the slow response time of intravenous sensors.

CONCLUSION

Although the concept of a fully implantable artificial beta cell has been validated as feasible, the limited performance in achieving glucose control requests improvements in the sensor structure to increase its longevity and decrease sensor delay.

Closing the loop: combining insulin pumps and glucose sensors in children with type 1 diabetes mellitus

Tight glycemic control of diabetic patients is associated with a reduction in the risk of microvascular and macrovascular complications, yet with elevated risk of severe episodes of hypoglycemia. The goal of "closing the loop" is to develop an autonomous insulin delivery system attached to a device capable of continuous glucose sensing, thus mimicking the islet beta cells activity and its capability of maintaining normal blood glucose levels and freeing the patient from the need of constant calculations of daily insulin and carbohydrates. The closed loop will protect patients from experiencing glucose excursions, including life-threatening events of hypoglycemia, thus improving glycemic control, reducing the fear from hypoglycemia and improving patients' quality of life. This review focuses on the steps towards closing the loop in the attempts to develop an artificial pancreas and on recent ongoing research and future directions in this field.

Implantable insulin pump therapy: an unusual presentation of a catheter-related complication

We report the case of a 63-year-old man who has a 19-year history of involvement in the implantable insulin pump program at Johns Hopkins University. After his most recent pump implantation in February 2004, his 24-h insulin requirement gradually increased from a baseline of 75 units to a peak of almost 500 units in June 2005. Surprisingly, insulin delivery from the pump and glycemic control remained satisfactory despite the dramatic change in insulin requirement. Laparotomy revealed a fibrous mass in the peritoneal cavity, with the track of the catheter extending into the mass. Insulin requirement declined post-resection of the mass and relocation of the catheter tip.

Controlled-release microchips

Efficient drug delivery remains an important challenge in medicine: continuous release of therapeutic agents over extended time periods in accordance with a predetermined temporal profile; local delivery at a constant rate to the tumour microenvironment to overcome much of the systemic toxicity and to improve antitumour efficacy; improved ease of administration, and increasing patient compliance required are some of the unmet needs of the present drug delivery technology. Microfabrication technology has enabled the development of novel controlled-release microchips with capabilities not present in the current treatment modalities. In this review, the current status and future prospects of different types of controlled-release microchips are summarised and analysed with reference to microneedle-based microchips, as well as providing an in-depth focus on microreservoir-based and nanoporous microchips.

Combined improvements in implantable pump technology and insulin stability allow safe and effective long term intraperitoneal insulin delivery in type 1 diabetic patients: the EVADIAC experience

OBJECTIVE

To report a long-term multicentre experience with implantable insulin pumps in type 1 diabetic patients, and to test safety and accuracy of the systems following improvements in infused insulin solutions and peritoneal catheter.

RESEARCH DESIGN AND METHODS

Forty MiniMed Implantable Pumps model 2001 were consecutively implanted over a two-month period in type 1 diabetic volunteers. The systems were equipped by a new compliant sideport catheter and were refilled at 45-day intervals with HOE 21 PH ETP insulin batches showing enhanced physical stability in vitro. Safety was assessed from the incidence of acute adverse events and effectiveness from quarterly HbA(1c) assays. Accuracy of delivery was measured at each pump refill by comparing residual insulin in the pump reservoir with expected amount according to programmed infusion. The study lasted until pump battery depletion or premature pump explantation.

RESULTS

Cumulated experience was 106 patient-years. Premature explantations occurred in 3 cases, due to one electronic pump failure and two "pump-pocket" infections. Near-normal insulin delivery was sustained until expected battery depletion in 13 cases. Forty underdelivery events occurred in 24 pumps, but 36 among them were related to pump slowdowns due to insulin aggregation in pumps that were promptly solved by an outpatient NaOH rinse procedure. Only 4 underdeliveries were caused by catheter obstructions that required laparoscopy to remove peritoneal tissue overgrowth around the catheter. Over pump lifetime, HbA(1c) was 7.2 +/- 0.2% in the 13 patients with no underdelivery and 7.7 +/- 0.5% in the other ones. Only one severe hypoglycemia and one ketoacidosis occurred during the whole study.

CONCLUSION

Our current experience with improved implantable pumps and insulin solutions shows both long-term safety and effectiveness of this treatment in type 1 diabetic patients following improvement in infused insulin solutions and catheter. This therapy may be a good alternative for patients that experience frequent severe hypoglycemia with intensive subcutaneous insulin therapy.

Reproducibility of plasma insulin kinetics during intraperitoneal insulin treatment by programmable pumps

OBJECTIVE

To study the reproducibility of plasma insulin kinetics during intraperitoneal (IP) insulin therapy using an implanted programmable pump in patients with type 1, insulin dependent, diabetes mellitus (IDDM).

RESEARCH DESIGN AND METHODS

In a group of ten type 1 IDDM patients beginning chronic IP insulin treatment with an implanted pump, plasma free insulin profiles were determined from 12: 00 am to 12: 30 pm on two separate test days, one month apart. Anti-insulin antibody (AIA) levels were measured on each test day.

RESULTS

From test day 1 to test day 2, no difference was observed in morning fasting free insulin levels (m +/- SD): 9.7 +/- 5.4 mU/L versus 9.8 +/- 5.3 mU/L, insulin peak values: 19.1 +/- 17 mU/L versus 20.8 +/- 9.9 mU/L, time to peak: 40 +/- 15 versus 42.8 +/- 16 minutes or post-bolus area under the plasma free insulin curve (AUC): 40.7 +/- 29 mU/L.h versus 45.5 +/- 29 mU/L.h. The intrapatient coefficient of variation was 14.4 +/- 13% for insulin peaks and 16.9 +/- 9.2% for post-bolus AUC. A significant increase in AIA levels (m +/- SD) was observed from 16.5 +/- 18% on test day 1 to 28.1 +/- 28% on test day 2.

CONCLUSIONS

The reproducibility of plasma free insulin profiles is highly satisfactory during insulin delivery by the IP route using an implanted device.

A novel use of U-500 insulin for continuous subcutaneous insulin infusion in patients with insulin resistance: a case series

OBJECTIVE

To report our experience with use of U-500 regular insulin (U-500) for continuous subcutaneous insulin infusion (CSII) in four patients with type 2 diabetes requiring high-dose insulin.

METHODS

We performed a retrospective review of medical records of four patients with type 2 diabetes and insulin resistance who were using U-500 in a CSII regimen for at least 6 months. Before treatment conversion, two patients were receiving CSII with use of insulin lispro, and two were receiving multiple daily insulin injections. Clinical assessment was monitored with glycosylated hemoglobin (HbA1c) levels. Changes in the insulin volume administered and associated cost savings are analyzed.

RESULTS

Three months after conversion to U-500 therapy, the average HbA1c decreased from 10.8% to 7.6%. By 6 months, it declined further to 7.3%. With use of U-500, the absolute volume of insulin infused per day decreased by at least fourfold. This volume reduction led to potential cost savings for insulin of up to $2,600 per year per patient and a savings for pump supplies of up to $3,400 per year per patient. All patients had subjective improvement in quality of life.

CONCLUSION

We propose that smaller volumes of insulin with use of U-500 allow for more efficient absorption of large doses of insulin and yield improved glycemic control. In our four patients, the use of U-500 for CSII resulted in improved quality of life, cost savings for treatment, and potential reduction in diabetes-related complications based on the decline in HbA1c. This treatment method may be a novel alternative for patients with type 2 diabetes and insulin resistance who have not met goal glycemic control with standard intensive regimens or who require insulin doses exceeding current insulin pump delivery capacity.

Continuous intraperitoneal insulin infusion in patients with 'brittle' diabetes: favourable effects on glycaemic control and hospital stay

AIMS

To evaluate the effects of continuous intraperitoneal insulin infusion (CIPII) using implantable pumps on glycaemic control and duration of hospital stay in poorly controlled 'brittle' Dutch diabetes patients, and to assess their current quality of life.

METHODS

Thirty-three patients were included. Glycaemic control was retrospectively assessed with HbA(1c) levels acquired before implantation, 1 year later and at long-term follow up of 58 months. Duration of hospital stay the year before and the year following first implantation was extracted from hospital records. Determinants of long-term glycaemic response were sought. Self-report questionnaires were administered at 58 months follow-up only, to assess current psychopathology and quality of life.

RESULTS

Mean HbA(1c) decreased from 10.0 +/- 2.3% to 9.0 +/- 1.8% (P = 0.039) 1 year after implantation and stabilized at 9.0 +/- 1.6% (P = 0.023) during long-term follow-up. Median number of hospital days in the 20 patients suffering from hospital admission before implantation decreased from 45 the year before implantation to 13 the year after (P = 0.005). Patients with a higher baseline HbA(1c) showed a larger long-term response (P < 0.001). Relatively low levels for quality of life were found, as well as a higher than expected number of patients with psychiatric symptoms.

CONCLUSIONS

CIPII proved effective in complex patients with a history of poor control and hospital admission. Despite a substantial long-term improvement in glycaemic control and diminished hospital stay, normal levels of glycaemic control and quality of life were not attained.

Insulin pump therapy in type 1 pediatric patients: now and into the year 2000

There are a number of medical conditions such as growth failure in children, pregnancy, lipid abnormalities, and early complications that are improved by the meticulous glycemic control that can be achieved with insulin pump therapy (CSII). By using an insulin pump, many patients with severe hypoglycemia, the dawn phenomenon, extremes of glycemic excursion, recurrent diabetic ketoacidosis (DKA) and hypoglycemia unawareness have amelioration of these problems. However, pump therapy involves problems such as weight gain, recurrent ketosis due to pump failure, infections, and risk of hypoglycemia. Owing to many developmental issues, young children may not be able to wear the pump without parental supervision. We have used the pump at night time only in these patients. This has allowed children of 7-10 years of age to benefit from improved nocturnal glycemia without the risk of pump therapy when they are without an adult to help. We have also used the pump in subjects with recurrent DKA and in our general patient population (mean age 13.6+/-3.9 years). In our pump cohort, CSII led to improvement in quality of life, knowledge, adherence, and responsibility. A reduction in hypoglycemia, DKA rate and mean HbA(1c) was associated with pump usage. For this to occur, however, pump education must be geared to the pediatric subject and his/her family. Education materials and tools help in learning how to use the pump and how to deal with the intricacies of basal and bolus dosing, and the effect of exercise, food and illness on diabetes management. The pump has improved since it was first introduced and these modifications have made it easier, more painless and less hazardous. With the development of continuous glucose sensors and implantable pumps, the next century will see pump therapy lead to the artificial pancreas.

Counterregulatory response to hypoglycemia differs according to the insulin delivery route, but does not affect glucose production in normal humans

The magnitude of the counterregulatory response to insulin-induced hypoglycemia is primarily determined by the degree of hypoglycemia. We examined whether the route of acute insulin delivery (portal or peripheral venous) is also important in determining the magnitude of the counterregulatory response to hypoglycemia in nine healthy nondiabetic men. Pancreatic insulin secretion, stimulated by an i.v. tolbutamide infusion (portal insulin study), was matched with an exogenous insulin infusion into the peripheral vein 4-6 weeks later (peripheral insulin study). Each study consisted of a 150-min baseline tracer equilibration period, a 180-min euglycemic hyperinsulinemic (portal or peripheral insulin delivery) period, a 60-min hypoglycemic period in which insulin secretion diminished during tolbutamide or was reduced during exogenous insulin, and a 30-min recovery period. Peripheral venous glucose concentrations were well matched in the portal and peripheral studies during euglycemia and hypoglycemia (glucose nadir, 2.9 +/- 0.1 mmol/L in the portal and 2.7 +/- 0.1 mmol/L in the peripheral; mean +/- SEM; P = NS), and insulin concentrations were about 1.5-fold higher throughout the experiment in the peripheral vs. the portal insulin study due to the first pass extraction of insulin in the portal study. There was a much greater increment (P < 0.0001) in FFA in the portal vs. the peripheral study (area under the curve: portal, 19.5 +/- 3.9 mmol/L x 90 min; peripheral, 3.3 +/- 1.1 mmol/L x 90 min), whereas plasma glucagon and GH were higher in the peripheral study (P = 0.01 for glucagon; P = 0.015 for GH). There was no significant difference between studies in epinephrine and norepinephrine responses to hypoglycemia or stimulation of endogenous glucose production (area under the curve: portal, 636 +/- 103 micromol/kg x 90 min; peripheral, 705 +/- 69 micromol/kg x 90 min; P = NS). In summary, we have shown that the glucagon, GH, and FFA responses to hypoglycemia during insulin dissipation are affected by the route of insulin delivery and are not controlled exclusively by the nadir blood glucose level. The clinical importance of these observations in diabetic subjects as they relate to route of insulin delivery (portal or peripheral) during insulin dissipation remains to be determined.

Surgical experience with implantable insulin pumps. Department of Veterans Affairs Implantable Insulin Pump Study Group

BACKGROUND

A recent Veterans Affairs cooperative trial demonstrated that intensive insulin therapy via an implantable pump with intraperitoneal insulin delivery reduced glycemic variability and improved quality of life compared with multiple daily insulin injections. Our aim was to determine perioperative morbidity and assess long-term function of the implantable insulin pump.

METHODS

Fifty-one adult patients with type 2 diabetes had infusion pumps placed over a 2-year period at seven VA Medical Centers as part of a randomized prospective study.

RESULTS

All pumps were placed successfully. There were two (4%) perioperative complications. There were no wound complications. Duration of pump use ranged from 12 to 25 months (mean 20). Catheter obstruction (57%) and pump malfunction (25%) were the most common reasons for pump explantation. Catheter occlusions increased after 12 months. Catheter occlusion was treated by percutaneous rinse procedure in 75% and revisional procedures in 31% of patients.

CONCLUSIONS

Implantable insulin pumps can be placed with minimal surgical morbidity. Attention to surgical detail and infusion protocol permits satisfactory long-term function. Pump/catheter complications increase with time but are usually resolvable by either operative or percutaneous manipulations.

Implanted programmable insulin pumps: one hundred fifty-three patient years of surgical experience

BACKGROUND

Implanted insulin pumps (IIPs) are an alternative treatment for diabetes mellitus. To maintain good glycemic control, patients with an IIP require frequent surgical interventions.

METHODS

Since November 1986, 21 patients with insulin-dependent diabetes mellitus at the Johns Hopkins Hospital have undergone implantation of pumps subcutaneously with a catheter delivering insulin into the peritoneal space. Patients were followed up with self-monitoring of blood glucose levels two to four times daily and percutaneous refills of the pump with U-400 insulin every 6 to 12 weeks.

RESULTS

In 153 patient-years, 77 pumps were placed. The mean pump life was 29 +/- 2 months. Morbidity was limited to pump site infections (3.9%) and one small bowel obstruction. Inadvertent insulin overdelivery has never occurred. Episodes of insulin underdelivery were caused by backflow anomalies (n = 67), which were cleared by percutaneous rinses, or catheter obstructions (n = 12), which required catheter replacements. Ninety-one operations were required to maintain pump function. All patients are alive and report improvements in quality of life. Significant reductions in hemoglobin A1C and plasma glucose levels were also seen.

CONCLUSIONS

Long-term use of IIPs results in significant improvements in clinical parameters and quality of life for individuals with insulin-dependent diabetes mellitus. Relatively frequent operations are required for maintaining pump function, which are done with a local anesthetic with minimal morbidity.

Novel forms of insulin delivery

Despite its widespread use, much is wrong with conventional subcutaneous insulin injection. It is more-or-less painful and inconvenient; it delivers insulin slowly with highly inconsistent pharmacokinetics into the peripheral venous system rather than directly to the liver via the portal vein; and, once delivered into the skin, it cannot be "turned off". This review has focused on novel alternative approaches to insulin delivery. The clinically available insulin delivery devices, such as pen injectors and external insulin pumps, are probably underutilized. Pen injectors offer convenience, whereas external pumps offer a basal/bolus approach to insulin delivery unlike that achieved by injections. Of the approaches currently under development, IPPs are closet to general availability. They have been extremely popular in more than 600 patients worldwide, however, an insulin problem has delayed application for their PMA in the United States. Feasibility studies of inhaled insulin, nasal insulin, and oral insulin have produced interesting preliminary findings, with pulmonary delivery for meal coverage with short-acting insulin having perhaps the brightest prospects. Encapsulated islets and biohybrid systems that place live islets into an implanted device are in earlier stages of development. Closing the loop with a continuous glucose sensor will be the only way to achieve truly normal blood glucose homeostasis by directing insulin delivery automatically on demand. Glucose sensors would have many other clinical applications in diabetes management in addition to driving a mechanical delivery system. However, the development of glucose sensing devices has been a formidable technical challenge. Based on an evaluation of current technologic development, glucose oxidase-based, needle-type sensors may become available within the next few years. Clinicians, the research community, and persons with diabetes can join in rejecting the notion that standard regimens of insulin injection do not need to be improved. If there is adequate incentive to continue a broad-based research effort into novel approaches to insulin delivery, the quality of life of persons with diabetes can be improved in the not too distant future.

Implantable insulin pumps: diagnosis and management of decreased flow rates using radionuclide investigation

The aim of this study was to develop a diagnostic procedure for pumping unit malfunction by radionuclide imaging (RI) and to validate the method by comparing the results with those obtained using more conventional methods. Fifteen radionuclide investigations were performed in 11 patients with intraperitoneal implantable insulin pumps. One mCi of 99 mTc in 1 ml isotonic sodium chloride was injected into the reservoir. The results based on catheter visualization and peritoneal accumulation were compared blindly to the efficacy of alkaline rinses and laparoscopic findings. In all RI stoppage cases except one alkaline rinses failed to restore flow. Where laparoscopy was performed, comparisons were concordant i.e. no outflow from the tip of the catheter. The RI images obtained were reproduced in vitro using a pump under normal flow conditions and complete proximal and distal catheter obstruction. RI is a safe, quick non invasive method which allows the location of the site of pump/catheter malfunction within a one step procedure and the prediction of the efficacy of sodium hydroxide rinses.

Use of an integrated sideport for diagnosis and management of decreased flow rates in a programmable implanted insulin delivery system. Implantable Insulin Pump Trial Study Group

The aim of this study was to develop procedures for the diagnosis and nonsurgical management of decreased insulin flow in an implantable programmable pump for long-term intraperitoneal or intravenous insulin delivery featuring a sideport. Patency of the catheter lumen was tested by measuring the time needed for sideport pressure to decrease by 50% after the injection of 0.1 ml of buffer solution. Pumping unit performances were assessed by measuring the volume of pump pulses after diverting the pump flow at the sideport. A catheter flush with buffer solution through the sideport was effective in clearing 79% of intraperitoneal and 84% of intravenous catheter occlusions. Washing the pumping unit with an alkaline solution after diverting pump flow at the sideport was effective in dissolving insulin aggregates inside the pumping unit and in restoring normal pump flow. These procedures were associated with a 1.3% rate of hypoglycemic episodes.

Postprandial insulin profiles with implantable pump therapy may explain decreased frequency of severe hypoglycemia, compared with intensive subcutaneous regimens, in insulin-dependent diabetes mellitus patients

PURPOSE

To examine the mechanism of the decreased frequency of severe hypoglycemia with implantable pump therapy compared with subcutaneous intensive therapy.

PATIENTS AND METHODS

Eight subjects with insulin-dependent diabetes mellitus (IDDM), enrolled in an implantable insulin pump study, were admitted to the General Clinical Research Center and on 2 separate days were given either a dose of preprandial insulin chosen to maintain normoglycemia for a standard (450 kcal, 50% carbohydrate) breakfast or 1.75 times the dose. The two doses were administered subcutaneously (by syringe or with an external pump) during one inpatient admission and by implantable pump (intraperitoneally, n=6; or intravenously, n=2) during a separate admission. Blood glucose, plasma-free insulin, and neurocognitive function were measured for 4 hours after the meal.

RESULTS

Subcutaneous administration resulted in 7 episodes of hypoglycemia (2 with the usual dose and 5 with the 1.75-fold dose), defined as blood glucose less than 50 mg/dL; implantable pump treatment resulted in only 2 episodes, both with the 1.75-fold dose (P <0.05, Fisher's two-tailed test for implantable versus subcutaneous). Compared with subcutaneous delivery, implantable pump therapy provided significantly lower insulin levels during the final 2 hours after administration of the usual dose and the 1.75-fold dose (P <0.005). In addition to the decreased frequency of hypoglycemia, implantable pump therapy resulted in significantly lower area under the glycemia curve during the first 120 minutes with the 1.75-fold dose compared with subcutaneous administration.

CONCLUSIONS

The lower frequency of severe hypoglycemia with intensive therapy administered by implantable pump therapy is explained by the more rapid clearance of insulin delivered intraperitoneally or intravenously compared with intensive subcutaneous injection regimens. The lower frequency of severe hypoglycemia with implantable pump therapy compared with subcutaneous therapy demonstrated in clinical trials is confirmed by this study, in which we attempted to induce hypoglycemia.

Application of computers in diabetes care--a review. I. Computers for data collection and interpretation

The paper reviews the contribution of information technology (IT) to diabetes care. An appraisal of this topic with respect to insulin-dependent (type 1) diabetic patients is carried out in view of the landmark findings of the Diabetes Control and Complications Trial (DCCT) which has demonstrated that maintaining tight blood glucose control can delay the onset and slow the progression of the later life complications of diabetes. The review starts with the clinical background and the main features of the control schema in which diabetic patients receive insulin therapy. An overview is then provided of recent IT initiatives in diabetes care, and the application of IT techniques to assist in the diagnosis and characterization of patients with diabetes mellitus is considered. The role of IT approaches for short-term glycaemic control is discussed and the utilization of computers for collecting, viewing and interpreting home monitoring blood glucose data is reviewed; both quantitative and qualitative techniques being considered. In the second paper the role of decision support tools for planning insulin therapy using clinical algorithms, hand-held devices, knowledge-based approaches, telemedicine techniques and interactive simulations is reviewed, and the validation and clinical evaluation of these tools is discussed. The likely impact of the routine clinical application of implantable/non-invasive blood glucose monitoring devices is also considered. Finally, the application of computers as teaching tools is reviewed and the ways in which such educational approaches might be applied for disseminating the benefits of the DCCT trial more widely are discussed.

Non-ophthalmologic findings of the Diabetes Control and Complications Trial

The Diabetes Control and Complications Trial (DCCT) was a large and rigorously conducted trial which definitively established that longterm hyperglycemia causes longterm diabetic complications. In this review the author considers the non-ophthalmologic results of the DCCT and the applications of these findings to current and future care of diabetic patients. It is concluded that people with diabetes do not need to anticipate a future of diabetic complications, and that improved glycemic control can be achieved through the education and cooperation of physicians, patients, and health care payers.

Immunogenicity of intraperitoneal insulin infusion using programmable implantable devices

Intraperitoneal insulin infusion using implantable devices in insulin-dependent diabetic (IDDM) patients is promising since it improves diabetic control and decreases frequency of hypoglycaemia. However, preliminary data show a striking increase in plasma levels of anti-insulin antibodies with this therapy. In order to more precisely evaluate the immunogenicity and its consequences, anti-insulin antibody levels in 62 IDDM patients were assessed every 3 months during a 2-year period following pump implantation. At the same time, diabetes control was evaluated with HbA1c, mean blood glucose levels, standard deviation of the daily blood glucose levels and the frequency of low blood glucose (< 3.58 mmol/l). Factors involved in antibody formation such as age, gender, HLA typing, and complement C4 alleles were also studied. After implantation, anti-insulin antibody levels increased significantly from 3.14% (range 0-26%) to 8.34% (0-49%) after 1 year and remained elevated. Patients were divided into two groups: responders able to show at least one antiinsulin antibody titre higher than 15% and non-responders whose titres were always lower than 6%. None of the factors studied was shown to statistically influence the anti-insulin antibody titres. Non-responders had significantly better metabolic results than the responders. Severe hypoglycaemic episodes decreased dramatically in both groups. Insulin requirements were comparable at time 0 and decreased initially in both groups. They remained low for the non-responders but returned to pre-implantation values for responders. Intraperitoneal insulin infusion led to a high immunogenetic response towards insulin in about half of the patients, leading to only moderately deleterious effects on metabolic control.(ABSTRACT TRUNCATED AT 250 WORDS)

Implantable insulin pumps and metabolic control

The development of implantable, remote-controlled insulin pumps dates back to the early 1970's when it was recognized that conventional insulin therapy may be inadequate to control microvascular complications. For the first prototypes the intraperitoneal access route was favoured because of a physiological portal/peripheral insulin gradient. With intraperitoneal insulin delivery excellent metabolic control can be obtained with glycohaemoglobin values close to the upper normal range. Although long-term studies in insulin-dependent diabetic patients show comparable results with respect to glycaemic control and intermediary substrate levels with intensive conventional therapy, the advantage of intraperitoneal insulin delivery may lie in the low rate of hypoglycaemic episodes.

Successful pregnancy in I.D.D.M. with intravenous programmable insulin pump

Management of subcutaneous insulin resistance remains a difficult problem which can be treated by administering insulin intravenously by means of infusion pumps. We wish to report the case of a 31 year old primigravida with subcutaneous insulin resistance who developed a hitherto undescribed clinical complication of clot formation at the catheter tip, successfully treated with anti-coagulant therapy. Previous publications on the use of pumps in pregnancy have reported on the intraperitoneal route for insulin administration.