Non-inferiority of insulin glargine versus insulin detemir on blood glucose variability in type 1 diabetes patients: a multicenter, randomized, crossover study

Insulin Glargine in Type 1 Diabetes Mellitus: A Review of Clinical Trials and Real-world Evidence Across Two Decades

BACKGROUND

Over the past two decades, insulin glargine 100 U/mL (Gla-100) has emerged as the "standard of care" basal insulin for the management of type 1 diabetes mellitus (T1DM). Both formulations, insulin glargine 100 U/mL (Gla-100) and glargine 300 U/mL (Gla- 300) have been extensively studied against various comparator basal insulins across various clinical and real-world studies. In this comprehensive article, we reviewed the evidence on both insulin glargine formulations in T1DM across clinical trials and real-world studies.

METHODS

Evidence in T1DM for Gla-100 and Gla-300 since their approvals in 2000 and 2015, respectively, were reviewed.

RESULTS

Gla-100 when compared to the second-generation basal insulins, Gla-300 and IDeg-100, demonstrated a comparable risk of overall hypoglycemia, but the risk of nocturnal hypoglycemia was higher with Gla-100. Additional benefits of Gla-300 over Gla-100 include a prolonged (>24- hours) duration of action, a more stable glucose-lowering profile, improved treatment satisfaction, and greater flexibility in the dose administration timing.

CONCLUSION

Both glargine formulations are largely comparable to other basal insulins in terms of glucose-lowering properties in T1DM. Further, risk of hypoglycemia is lower with Gla-100 than Neutral Protamine Hagedorn but comparable to insulin detemir.

A Comprehensive Review of the Evolution of Insulin Development and Its Delivery Method

The year 2021 marks the 100th anniversary of the momentous discovery of insulin. Through years of research and discovery, insulin has evolved from poorly defined crude extracts of animal pancreas to recombinant human insulin and analogues that can be prescribed and administered with high accuracy and efficacy. However, there are still many challenges ahead in clinical settings, particularly with respect to maintaining optimal glycemic control whilst minimizing the treatment-related side effects of hypoglycemia and weight gain. In this review, the chronology of the development of rapid-acting, short-acting, intermediate-acting, and long-acting insulin analogues, as well as mixtures and concentrated formulations that offer the potential to meet this challenge, are summarized. In addition, we also summarize the latest advancements in insulin delivery methods, along with advancement to clinical trials. This review provides insights on the development of insulin treatment for diabetes mellitus that may be useful for clinicians in meeting the needs of their individual patients. However, it is important to note that as of now, none of the new technologies mentioned have superseded the existing method of subcutaneous administration of insulin.

Efficacy and safety of insulin detemir versus glargine in patients with diabetes: a systematic review and meta-analysis

OBJECTIVES

: Performing an updated meta-analysis to compare the safety and efficacy of insulin glargine and insulin detemir in adults with type 1 and type 2 diabetes.

METHODS

: Electronic databases were searched up to August 18, 2021. A random-effects model was applied to pool data from included studies to calculate the standardized mean differences (SMDs) for the continuous variables and relative risks (RRs) for the dichotomous variable.

RESULTS

: Nine studies compared insulin detemir and insulin glargine in type 2 diabetes and three studies in patients with type 1 diabetes. The pooled SMD of weight gain was -0.59 (95% CI -1.05 to -0.14; P=0.01; I²=98%) in patients with type 2 diabetes. The pooled RR of severe hypoglycemia was 0.28 (95% CI 0.12 to 0.63; P=0.002; I²=0%) in patients with type 1 diabetes. The effects of detemir and glargine on HbA1c, fasting plasma glucose, nocturnal hypoglycemia, and overall hypoglycemia were not statistically different (P>0.05).

CONCLUSIONS

It was found that there is no clinically considerable difference between the impacts of insulin detemir and insulin glargine in diabetic patients. The only statistically significant differences were less weight gain in type 2 diabetes and fewer episodes of severe hypoglycemia in type 1 diabetes with insulin detemir.

Synthetic long-acting insulin analogs for the management of type 1 diabetes: an update

INTRODUCTION

Type 1 diabetes is characterized by insulin deficiency and requires near-physiological insulin replacement. In most patients, this is accomplished by basal bolus therapy consisting of a long-acting basal insulin administered once or twice daily and short-acting insulin with main meals. Several long-acting insulin analogs have been developed to optimize basal insulin therapy.

AREAS COVERED

This paper reviews the design of - and data from - randomized controlled trials (RCTs) to assess glucose lowering efficacy and safety of long-acting insulin analogs for the treatment of type 1 diabetes.

EXPERT OPINION

Due to the non-inferiority treat-to-target design of insulin, RCTs treatment differences primarily appear as differences in hypoglycemia risk. Data suggest that the first generation long-acting insulin analogs insulin glargine U100 and insulin detemir have a similar glucose lowering efficacy compared to NPH insulin but a lower risk of hypoglycemia, particularly during nighttime. The newer analogs insulin glargine U300 and insulin degludec provide non-inferior efficacy, although insulin glargine U300 is less potent unit-to-unit. Insulin degludec reduces hypoglycemia risk compared to insulin glargine U100. Future studies should explore the potential for further improvement of treatment results in type 1 diabetes by a structured approach to personalization of basal insulin therapy.

Glycemic Variability With Insulin Glargine Versus Detemir in Hospitalized Patients With Diabetes

BACKGROUND

Prior research has demonstrated increased mortality with increasing glycemic variability (GV) in hospitalized patients with diabetes.

OBJECTIVE

We aimed to compare glycemic variability (GV) of insulin glargine to detemir in the inpatient setting.

METHODS

This single-center, retrospective, cohort study evaluated noncritically ill patients with diabetes on long-acting insulin at a large academic medical institution between 2010 and 2017. This study was reviewed and approved by the Institutional Review Board. The formulary transitioned from insulin glargine to detemir in December 2013; therefore, patients were compared before and after transition. The primary endpoint was to compare coefficient of variation (CV), a measure of GV, between detemir and glargine. Secondary endpoints included GV measured by standard deviation (SD), CV within 72 hours of long-acting insulin initiation, length-of-stay (LOS), in-hospital mortality, and comparison between subgroups.

RESULTS

2334 patients were included in the study, and there were 1167 in each group. CV was significantly less variable with detemir compared to glargine (33.7% versus 34.8%, difference = 1.09, p = 0.02) and remained significant after controlling for confounders. Similarly, SD was significantly less with detemir (p = 0.048). CV within 72 hours, LOS, and in-hospital mortality were not statistically different. Lastly, GV was higher in medical patients compared to surgical.

CONCLUSION

Insulin detemir exhibited less GV than insulin glargine, although the small difference is unlikely to be clinically significant. Application of this data will aid in formulary decisions and support the use of either agent within the hospital setting.

A review of the NG17 recommendations for the use of basal insulin in type 1 diabetes

AIMS

To revisit the data analysis used to inform National Institute of Health and Care Excellence (NICE) NG17 guidance for initiating basal insulin in adults with type 1 diabetes mellitus (diabetes).

METHODS

We replicated the data, methodology and analysis used by NICE diabetes in the NG17 network meta-analysis (NMA). We expanded this data cohort to a more contemporary data set (extended 2017 NMA) and restricted the studies included to improve the robustness of the data set (restricted 2017 NMA) and in a post hoc analysis, changed the index comparator from neutral protamine Hagedorn (NPH) insulin twice daily to insulin detemir twice daily.

RESULTS

The absolute changes in HbA_1c were similar to those reported in the NG17. However, all 95% credible intervals for change in HbA_1c point estimates crossed the line of null effect, except for detemir twice daily (in the NICE and extended 2017 NMAs) and NPH four times daily. In the detemir twice-daily centred post hoc analysis, the 95% credible intervals for change in HbA_1c crossed the line of null effect for all basal therapies, except NPH.

CONCLUSIONS

In NG17, comparisons of basal insulins were based solely on efficacy of glycaemic control. Many of the trials used in this analysis were treat-to-target, which minimize differences in HbA_1c . In the NMAs, statistical significance was severely undermined by the wide credible intervals. Despite these limitations, point estimates of HbA_1c were used to rank the insulins and formed the basis of NG17 guidance. This study queries whether such analyses should be used to make specific clinical recommendations.

Insulin Therapy in Adults with Type 1 Diabetes Mellitus: a Narrative Review

Here, we review insulin management options and strategies in nonpregnant adult patients with type 1 diabetes mellitus (T1DM). Most patients with T1DM should follow a regimen of multiple daily injections of basal/bolus insulin, but those not meeting individual glycemic targets or those with frequent or severe hypoglycemia or pronounced dawn phenomenon should consider continuous subcutaneous insulin infusion. The latter treatment modality could also be an alternative based on patient preferences and availability of reimbursement. Continuous glucose monitoring may improve glycemic control irrespective of treatment regimen. A glycemic target of glycated hemoglobin < 7% (53 mmol/mol) is appropriate for most nonpregnant adults. Basal insulin analogues with a reduced peak profile and an extended duration of action with lower intraindividual variability relative to neutral protamine Hagedorn insulin are preferred. The clinical advantages of basal analogues compared with older basal insulins include reduced injection burden, better efficacy, lower risk of hypoglycemic episodes (especially nocturnal), and reduced weight gain. For prandial glycemic control, any rapid-acting prandial analogue (aspart, glulisine, lispro) is preferred over regular human insulin. Faster-acting insulin aspart is a relatively new option with the advantage of better postprandial glucose coverage. Frequent blood glucose measurements along with patient education on insulin dosing based on carbohydrate counting, premeal blood glucose, and anticipated physical activity is paramount, as is education on the management of blood glucose under different circumstances.Plain Language Summary: Plain language summary is available for this article.

Evaluation of Unit Equivalency of Insulin Glargine to Insulin Detemir in an Acute Care Setting

Background: Insulin glargine and insulin detemir are the most commonly prescribed basal insulins in the United States. While these analogs chemically differ, clinical trials have established no significant difference in efficacy. However, controversy remains as to whether the 2 agents are comparable with regard to unit equivalency. Objectives: To determine the ratio of glucose lowering between insulin detemir and insulin glargine. Methods: This institutional review board-approved, single-center, retrospective, case-crossover study was conducted in patients with diabetes mellitus with inpatient admissions between June 30, 2014, to July 1, 2015. Patients must have received both insulin detemir and insulin glargine on either the same or separate hospital visits. A blood glucose–lowering ratio for both insulin glargine and insulin detemir was calculated for each patient based off of up to 5 days of fasting blood glucose values and the total number of units of insulin administered. Results: Fifty-two patients were included in this study. No significant difference was found in the blood glucose–lowering ratio between insulin glargine (0.23 mg/dL/unit) as compared with insulin detemir (0.16 mg/dL/unit; P = .08). Conclusion: No difference was found in the blood glucose–lowering ratio between insulin glargine and insulin detemir. The results of this study suggest that conversion between insulin glargine and insulin detemir using a 1:1 ratio in an acute care setting may be appropriate.

Glycemic Control in Adult Type 1 Diabetes Patients with Insulin Glargine, Insulin Detemir, or Continuous Subcutaneous Insulin Infusion in Daily Practice

BACKGROUNDS

This study aims to compare glycemic control of persons with type 1 diabetes using multiple daily injections (MDI) with insulin glargine versus insulin detemir or with continuous subcutaneous insulin infusion (CSII) in daily practice.

SUBJECTS AND METHODS

All adult individuals with type 1 diabetes (n = 1053) were identified from the electronic patient database in North Karelia, Finland. The persons' individual data for insulin treatment, diabetic ketoacidosis (DKA), and hemoglobin A_1c (HbA1c) measurements during the year 2014 were obtained from medical records. Persons using long-acting insulin analogs or CSII were included in the analyses (n = 1004).

RESULTS

Altogether, 47.7% used glargine, 43.9% used detemir, and 8.4% used CSII. The mean HbA1c was lower in the CSII group (63 mmol/mol [7.9%]) compared with the glargine group (66 mmol/mol [8.2%]) or the detemir group (67 mmol/mol [8.3%]). The overall rate of DKA was 5.1% per year. The rate of DKA was higher in the detemir group compared with the glargine group (6.3% per year vs. 3.8% per year, respectively, P < 0.049). In logistic regression analyses, the higher rate of DKA with detemir use was explained by HbA1c.

CONCLUSIONS

In daily practice, the glycemic control of type 1 diabetes patients with MDI was similar regardless of basal insulin, glargine, or detemir, whereas CSII allowed better glycemic control than MDI. The rate of DKA was higher with detemir than with glargine, but this is likely related to higher HbA1c rather than insulin regimen.

Basal Insulin Regimens for Adults with Type 1 Diabetes Mellitus: A Systematic Review and Network Meta-Analysis

OBJECTIVE

To assess the relative efficacy and safety of basal insulin regimens in adults with type 1 diabetes mellitus (T1DM).

METHODS

A systematic review and Bayesian network meta-analysis (NMA) of randomized controlled trials comparing two or more basal insulin regimens were conducted. The following basal insulin regimens were included: Neutral Protamine Hagedorn (iNPH) (once [od], twice [bid], and four times daily [qid]), insulin detemir (iDet) (od and bid), insulin glargine 100 IU (iGlarg) (od), and insulin degludec (iDegl) (od). We searched the following databases: MEDLINE via OVID, Embase via OVID, and the Cochrane Library (Wiley). Study quality was appraised using Cochrane risk-of-bias checklist for randomized controlled trials. Two outcomes (change in hemoglobin A_1c [HbA_1c] and rate of severe/major hypoglycemia [SH]) were analyzed. Network inconsistency was assessed using Bucher and chi-square tests.

RESULTS

Thirty studies met the eligibility criteria. Twenty-five were included in the HbA_1c network and 16 in the SH network. All studies were of moderate quality. No network inconsistency was evident in the HbA_1c network. Of the seven regimens of interest, iDet (bid) had the highest probability of being best (mean change in HbA_1c -0.48; 95% credible interval -0.69 to -0.29). In contrast, the SH network demonstrated both considerable uncertainty and significant network inconsistency (χ² test, P = 0.003).

CONCLUSIONS

Of the specified frequency regimens, iDet (bid) had the highest probability of being the best basal insulin regimen in terms of reduction in HbA_1c. Ranking of the regimens in terms of the SH rate was highly uncertain and no clear conclusion could be made.

Basal Insulin Regimens for Adults with Type 1 Diabetes Mellitus: A Cost-Utility Analysis

OBJECTIVES

To assess the cost-effectiveness of basal insulin regimens for adults with type 1 diabetes mellitus in England.

METHODS

A cost-utility analysis was conducted in accordance with the National Institute for Health and Care Excellence reference case. The UK National Health Service and personal and social services perspective was used and a 3.5% discount rate was applied for both costs and outcomes. Relative effectiveness estimates were based on a systematic review of published trials and a Bayesian network meta-analysis. The IMS CORE Diabetes Model was used, in which net monetary benefit (NMB) was calculated using a threshold of £20,000 per quality-adjusted life-year (QALY) gained. A wide range of sensitivity analyses were conducted.

RESULTS

Insulin detemir (twice daily) [iDet (bid)] had the highest mean QALY gain (11.09 QALYs) and NMB (£181,456) per patient over the model time horizon. Compared with the lowest cost strategy (insulin neutral protamine Hagedorn once daily), it had an incremental cost-effectiveness ratio of £7844/QALY gained. Insulin glargine (od) [iGlarg (od)] and iDet (od) were ranked as second and third, with NMBs of £180,893 and £180,423, respectively. iDet (bid) remained the most cost-effective treatment in all the sensitivity analyses performed except when high doses were assumed (>30% increment compared with other regimens), where iGlarg (od) ranked first.

CONCLUSIONS

iDet (bid) is the most cost-effective regimen, providing the highest QALY gain and NMB. iGlarg (od) and iDet (od) are possible options for those for whom the iDet (bid) regimen is not acceptable or does not achieve required glycemic control.

Comparison of Insulin Detemir and Insulin Glargine for Hospitalized Patients on a Basal-Bolus Protocol

BACKGROUND: The primary purpose of this study is to determine whether insulin detemir is equivalent to insulin glargine in controlling hyperglycemia for the adult hospitalized patient on a basal-bolus treatment regimen. METHODS: A retrospective study was conducted at two acute care hospitals within the same health system. Patients from both facilities who were initiated on a basal-bolus subcutaneous insulin regimen were included in the study. The basal-bolus regimen consisted of three components: basal, bolus, and corrective insulin with only the data from the first seven days analyzed. Once the basal-bolus protocol was initiated, all previous glycemic agents were discontinued. The target glycemic goal of the study was 100–180 mg/dL. RESULTS: In both groups, 50% of the patients had achieved the target glycemic control goal (100–180 mg/dL) by day 2 (p = 0.3). However, on the seventh or last day of basal-bolus treatment, whichever came first, 36.36% of patients receiving insulin detemir (n = 88) achieved the blood glucose reading goal compared to 52.00% in patients receiving insulin glargine (n = 100) (p = 0.03). This corresponded to an adjusted odds ratio of 2.12 (1.08 to 4.15), p = 0.03. The adjusting variables were provider type, whether the patient was hospitalized within 30 days prior and diagnosis of stroke. The mean blood glucose readings for the insulin glargine and the insulin detemir groups while on basal-bolus therapy were 200 mg/dL and 215 mg/dL, respectively (p = 0.05). The total number of blood glucose readings less than 70 mg/dL and less than 45 mg/dL was very low and there were no differences in number of episodes with hypoglycemia between the two groups. CONCLUSION: There was not a statistical difference between the two groups at 2 days, however there was on the seventh day or the last day of basal-bolus treatment. There were nonsignificant hypoglycemia events between basal insulin groups and the results for the last or seventh day of treatment may not be clinically significant in practice.

The past, present, and future of basal insulins

Insulin production by the pancreas follows a basic pattern where basal levels of insulin are secreted during fasting periods, with prandial increases in insulin associated with food ingestion. The aim of insulin therapy in patients with diabetes is to match the endogenous pattern of insulin secretion as closely as possible without causing hypoglycaemia. There are several optimal pharmacokinetic and pharmacodynamic properties of long-acting basal insulins that can help to achieve this aim, namely, as follows: activity that is flat and as free of peaks as possible, a duration of action of ≥24-h, and as little day-to-day variation as possible. The long-acting basal insulins are a fundamental therapy for patients with type 1 and type 2 diabetes, and those that are currently available have many benefits; however, the development of even longer-acting insulins and improved insulin delivery techniques may lead to better glycemic control for patients in the future. Established long-acting basal insulins available in the United States and Europe include insulin glargine 100 units/mL and insulin detemir, both of which exhibit similar glycemic control to that of the intermediate-acting neutral protamine Hagedorn insulin, but with a reduction in hypoglycaemia. Newer insulin products available include new insulin glargine 300 units/mL (United States and Europe) and the ultra-long-acting insulin degludec (Europe) with basal insulin peglispro currently in development. These new insulins demonstrate different pharmacokinetic/pharmacodynamic profiles and longer durations of action (>24 h) compared with insulin glargine 100 units/mL, which may lead to potential benefits. The introduction of biosimilar insulins may also broaden access to insulins by reducing treatment costs. Copyright © 2015 John Wiley & Sons, Ltd.

Systematic literature review of use of blood glucose monitoring in phase III clinical studies of insulin analogs

BACKGROUND

Safe and effective insulin therapy for diabetes mellitus requires initial dose titration and regular adjustments based on blood glucose (BG) monitoring. Our objective was to explore the use of BG measurement in phase-III clinical studies of insulin analogs. These studies provide safety and efficacy information for regulatory authorities and are the basis for insulin analog regulatory approval.

METHODS

A systematic review of phase-III studies of rapid-acting insulin analogs (insulin lispro, insulin aspart and insulin glulisine) and pre-mixed insulin analogs (biphasic insulin aspart and insulin lispro mix) was conducted. Studies were identified using manufacturers' databases. Search for reports was performed in Medline and registry of clinical trials (clinicaltrials.gov). The European Medicines Agency was contacted to provide Clinical Study Reports.

RESULTS

Forty-five studies were included. Regular BG measurements were reported in 100 % of the studies and were performed by either self-monitoring of blood glucose (SMBG) alone in 84 %, laboratory alone in 7 %, and both SMBG and laboratory in 9 % of studies. In total, 93 % of the studies reported SMBG. Most studies (91 %) reported insulin therapy adjustments based on BG measurements.

CONCLUSIONS

The findings suggest that BG monitoring and specifically SMBG are co-dependent technologies with insulin analogs. BG measurement is used in most phase-III registration studies for establishing safe and efficacious insulin administration and is recommended in the insulin labels. The indispensable role of SMBG in treatment of insulin-dependent patients should receive attention from health care payers to assess and reimburse SMBG along with insulin to avoid adverse events from inappropriate insulin administration and associated costs.

Safety, effectiveness, and cost effectiveness of long acting versus intermediate acting insulin for patients with type 1 diabetes: systematic review and network meta-analysis

OBJECTIVE

To examine the safety, effectiveness, and cost effectiveness of long acting insulin for type 1 diabetes.

DESIGN

Systematic review and network meta-analysis.

DATA SOURCES

Medline, Cochrane Central Register of Controlled Trials, Embase, and grey literature were searched through January 2013.

STUDY SELECTION

Randomized controlled trials or non-randomized studies of long acting (glargine, detemir) and intermediate acting (neutral protamine Hagedorn (NPH), lente) insulin for adults with type 1 diabetes were included.

RESULTS

39 studies (27 randomized controlled trials including 7496 patients) were included after screening of 6501 titles/abstracts and 190 full text articles. Glargine once daily, detemir once daily, and detemir once/twice daily significantly reduced hemoglobin A1c compared with NPH once daily in network meta-analysis (26 randomized controlled trials, mean difference -0.39%, 95% confidence interval -0.59% to -0.19%; -0.26%, -0.48% to -0.03%; and -0.36%, -0.65% to -0.08%; respectively). Differences in network meta-analysis were observed between long acting and intermediate acting insulin for severe hypoglycemia (16 randomized controlled trials; detemir once/twice daily versus NPH once/twice daily: odds ratio 0.62, 95% confidence interval 0.42 to 0.91) and weight gain (13 randomized controlled trials; detemir once daily versus NPH once/twice daily: mean difference 4.04 kg, 3.06 to 5.02 kg; detemir once/twice daily versus NPH once daily: -5.51 kg, -6.56 to -4.46 kg; glargine once daily versus NPH once daily: -5.14 kg, -6.07 to -4.21). Compared with NPH, detemir was less costly and more effective in 3/14 cost effectiveness analyses and glargine was less costly and more effective in 2/8 cost effectiveness analyses. The remaining cost effectiveness analyses found that detemir and glargine were more costly but more effective than NPH. Glargine was not cost effective compared with detemir in 2/2 cost effectiveness analyses.

CONCLUSIONS

Long acting insulin analogs are probably superior to intermediate acting insulin analogs, although the difference is small for hemoglobin A1c. Patients and their physicians should tailor their choice of insulin according to preference, cost, and accessibility.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42013003610.

Flexibly timed once-daily dosing with degludec: a new ultra-long-acting basal insulin

Insulin treatment in type 1 and type 2 diabetes (T1D and T2D) is highly efficacious, but in practice, non-adherence and ineffective dose titration limit its effectiveness. Barriers to more effective insulin treatment are numerous, including hypoglycaemia, fear of hypoglycaemia and concern about weight gain. The regular treatment timing needed with conventional basal insulins [neutral protamine Hagedorn (NPH) insulin and the first-generation analogues glargine and detemir] may also make adherence to these treatments problematic for many patients. Indeed, surveys indicate that the rigidity of this schedule induces some patients with T1D and T2D to omit insulin doses. Degludec is a novel, ultra-long-acting basal insulin analogue that is as effective as insulin glargine, but significantly reduces patients' risk of nocturnal hypoglycaemia. Because of its peakless, extended and highly predictable glucose-lowering effect, once-daily dosing on a flexible schedule may be feasible with degludec. Studies testing this possibility suggest that degludec tolerates day-to-day variation in dose timing while maintaining full efficacy and low risk of nocturnal hypoglycaemia. Degludec would appear to be an appropriate choice for patients being considered for a basal analogue, and it may be particularly well suited to patients with unpredictable social or work schedules, those who travel frequently and those who find rigid scheduling of their insulin injections a burden or barrier to regular treatment.

Minimal functional β-cell mass in intraportal implants that reduces glycemic variability in type 1 diabetic recipients

OBJECTIVE

Previous work has shown a correlation between β-cell number in cultured islet cell grafts and their ability to induce C-peptide secretion after intraportal implantation in C-peptide-negative type1 diabetic patients. In this cross-sectional study, we examined the minimal functional β-cell mass (FBM) in the implant that induces metabolic improvement.

RESEARCH DESIGN AND METHODS

Glucose clamps assessed FBM in 42 recipients with established implants. C-peptide release during each phase was expressed as percentage of healthy control values. Its relative magnitude during a second hyperglycemic phase was most discriminative and therefore selected as a parameter to be correlated with metabolic effects.

RESULTS

Recipients with functioning β-cell implants exhibited average FBM corresponding to 18% of that in normal control subjects (interquartile range 10-33%). Its relative magnitude negatively correlated with HbA1c levels (r = -0.47), daily insulin dose (r = -0.75), and coefficient of variation of fasting glycemia (CVfg) (r = -0.78, retained in multivariate analysis). A correlation between FBM and CVfg <25% appeared from the receiver operating characteristic curve (0.97 [95% CI 0.93-1.00]). All patients with FBM >37% exhibited CVfg <25% and a >50% reduction of their pretransplant CVfg; this occurred in none with FBM <5%. Implants with FBM >18% reduced CVfg from a median pretransplant value of 46 to <25%.

CONCLUSIONS

Glucose clamping assesses the degree of restoration in FBM achieved by islet cell implants. Values >37% of normal control subjects appear needed to reduce glycemic variability in type 1 diabetic recipients. Further studies should examine whether the test can help guide decisions on additional islet cell transplants and on adjusting or stopping immunotherapy.