Comparison of human insulin and insulin analogues on hypoglycaemia and metabolic variability in type 1 diabetes using standardized measurements (HYPO score and Lability Index)

Use of Analog and Human Insulin in a European Hemodialysis Cohort With Type 2 Diabetes: Associations With Mortality, Hospitalization, MACE, and Hypoglycemia

RATIONALE & OBJECTIVE

Poor glycemic control may contribute to the high mortality rate in patients with type 2 diabetes receiving hemodialysis. Insulin type may influence glycemic control, and its choice may be an opportunity to improve outcomes. This study assessed whether treatment with analog insulin compared with human insulin is associated with different outcomes in people with type 2 diabetes and kidney failure receiving hemodialysis.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

People in the Analyzing Data, Recognizing Excellence and Optimizing Outcomes (AROii) study with kidney failure commencing hemodialysis and type 2 diabetes being treated with insulin within 288 dialysis facilities between 2007 and 2009 across 7 European countries. Study participants were followed for 3 years. People with type 1 diabetes were excluded using an established administrative data algorithm.

EXPOSURE

Treatment with an insulin analog or human insulin.

OUTCOME

All-cause mortality, major adverse cardiovascular events (MACE), all-cause hospitalization, and confirmed hypoglycemia (blood glucose<3.0mmol/L sampled during hemodialysis).

ANALYTICAL APPROACH

Inverse probability weighted Cox proportional hazards models to estimate hazard ratios for analog insulin compared with human insulin.

RESULTS

There were 713 insulin analog and 733 human insulin users. Significant variation in insulin type by country was observed. Comparing analog with human insulin at 3 years, the percentage of patients experiencing end points and adjusted hazard ratios (AHR) were 22.0% versus 31.4% (AHR, 0.808 [95% CI, 0.66-0.99], P=0.04) for all-cause mortality, 26.8% versus 35.9% (AHR, 0.817 [95% CI, 0.68-0.98], P=0.03) for MACE, and 58.2% versus 75.0% (AHR, 0.757 [95% CI, 0.67-0.86], P<0.001) for hospitalization. Hypoglycemia was comparable between insulin types at 14.1% versus 15.0% (AHR, 1.169 [95% CI, 0.80-1.72], P=0.4). Consistent strength and direction of the associations were observed across sensitivity analyses.

LIMITATIONS

Residual confounding, lack of more detailed glycemia data.

CONCLUSIONS

In this large multinational cohort of people with type 2 diabetes and kidney failure receiving maintenance hemodialysis, treatment with analog insulins was associated with better clinical outcomes when compared with human insulin.

PLAIN-LANGUAGE SUMMARY

People with diabetes who are receiving dialysis for kidney failure are at high risk of cardiovascular disease and death. This study uses information from 1,446 people with kidney failure from 7 European countries who are receiving dialysis, have type 2 diabetes, and are prescribed either insulin identical to that made in the body (human insulin) or insulins with engineered extra features (insulin analog). After 3 years, fewer participants receiving analog insulins had died, had been admitted to the hospital, or had a cardiovascular event (heart attack, stroke, heart failure, or peripheral vascular disease). These findings suggest that analog insulins should be further explored as a treatment leading to better outcomes for people with diabetes on dialysis.

Pharmacokinetic and pharmacodynamic similarity evaluation between an insulin glargine biosimilar product and Lantus® in healthy subjects: Pharmacokinetic parameters of both parent insulin glargine and M1 were used as endpoints

Insulin glargine is a long-acting insulin analog, which plays an important role in the treatment of diabetes mellitus. Biosimilar products of insulin glargine can provide patients with additional safe, high-quality, and potentially cost-effective options for treating diabetes. This article presents a randomized, double-blind, single-dose, two-treatment, four-period, replicate crossover, euglycemic clamp study which was designed to evaluate the PK and PD similarity between the recombinant insulin glargine developed by Wanbang (test) and Lantus® (reference) in healthy volunteers. Subjects received subcutaneous administration of the insulin glargine formulation (0.4 U/kg) on two occasions for the test and reference drug, respectively, and a 20% dextrose solution was infused at variable rate to clamp the blood glucose concentrations at 0.3 mmol/L below the subjects’ fasting glucose for 24 h. Taking advantage of the improved sensitivity of the bioanalytical method applied and the solution of the matrix stability problem, the parent insulin glargine was determined in the vast majority of plasma samples using a fully validated UHPLC-MS/MS method. The PK characteristics of the parent insulin glargine were revealed for the first time: after subcutaneous injection, concentrations of the parent insulin glargine increased to a relative high level within 3 h, and then, a relatively flat concentration–time profile lasting for at least 12 h post-dose was observed. For the first time, the pharmacokinetic parameters of the parent insulin glargine were used as endpoints for similarity evaluation, which complied with the regulatory guidance better and made the similarity conclusion more powerful. The ratios of geometric means of all PK and PD endpoints were close to 100.00%. For the PK endpoints (AUC0–24h, Cmax, AUC0–12h, and AUC12–24h of the parent insulin glargine and its metabolite M1), the 90% confidence intervals of geometric mean ratios of test to reference were entirely contained within 80.00%–125.00%. For the PD endpoints [AUCGIR(0–24h), GIRmax, AUCGIR(0–12h), and AUCGIR(12–24h)], the 95% confidence intervals of geometric mean ratios of test to reference were entirely contained within 80.00%–125.00%. Based on the above mentioned results, it can be concluded that the PK and PD characteristics of the biosimilar drug developed by Wanbang are similar to those of Lantus.

(Ultra-)long-acting insulin analogues for people with type 1 diabetes mellitus

BACKGROUND

People with type 1 diabetes mellitus (T1DM) need treatment with insulin for survival. Whether any particular type of (ultra-)long-acting insulin provides benefit especially regarding risk of diabetes complications and hypoglycaemia is unknown.

OBJECTIVES

To compare the effects of long-term treatment with (ultra-)long-acting insulin analogues to NPH insulin (neutral protamine Hagedorn) or another (ultra-)long-acting insulin analogue in people with type 1 diabetes mellitus.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, Scopus, ClinicalTrials.gov, the World Health Organization (WHO) International Clinical Trials Registry Platform and the reference lists of systematic reviews, articles and health technology assessment reports. We explored the US Food and Drug Administration (FDA) and European Medical Agency (EMA) web pages. We asked pharmaceutical companies, EMA and investigators for additional data and clinical study reports (CSRs). The date of the last search of all databases was 24 August 2020.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) with a duration of 24 weeks or more comparing one (ultra-)long-acting insulin to NPH insulin or another (ultra-)long-acting insulin in people with T1DM.

DATA COLLECTION AND ANALYSIS

Two review authors assessed risk of bias using the new Cochrane 'Risk of bias' 2 (RoB 2) tool and extracted data. Our main outcomes were all-cause mortality, health-related quality of life (QoL), severe hypoglycaemia, non-fatal myocardial infarction/stroke (NFMI/NFS), severe nocturnal hypoglycaemia, serious adverse events (SAEs) and glycosylated haemoglobin A1c (HbA1c). We used a random-effects model to perform meta-analyses and calculated risk ratios (RRs) and odds ratios (ORs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes, using 95% confidence intervals (CIs) and 95% prediction intervals for effect estimates. We evaluated the certainty of the evidence applying the GRADE instrument.

MAIN RESULTS

We included 26 RCTs. Two studies were unpublished. We obtained CSRs, clinical study synopses or both as well as medical reviews from regulatory agencies on 23 studies which contributed to better analysis of risk of bias and improved data extraction. A total of 8784 participants were randomised: 2428 participants were allocated to NPH insulin, 2889 participants to insulin detemir, 2095 participants to insulin glargine and 1372 participants to insulin degludec. Eight studies contributing 21% of all participants comprised children. The duration of the intervention varied from 24 weeks to 104 weeks. Insulin degludec versus NPH insulin: we identified no studies comparing insulin degludec with NPH insulin. Insulin detemir versus NPH insulin (9 RCTs): five deaths reported in two studies including adults occurred in the insulin detemir group (Peto OR 4.97, 95% CI 0.79 to 31.38; 9 studies, 3334 participants; moderate-certainty evidence). Three studies with 870 participants reported QoL showing no true beneficial or harmful effect for either intervention (low-certainty evidence). There was a reduction in severe hypoglycaemia in favour of insulin detemir: 171/2019 participants (8.5%) in the insulin detemir group compared with 138/1200 participants (11.5%) in the NPH insulin group experienced severe hypoglycaemia (RR 0.69, 95% CI 0.52 to 0.92; 8 studies, 3219 participants; moderate-certainty evidence). The 95% prediction interval ranged between 0.34 and 1.39. Only 1/331 participants in the insulin detemir group compared with 0/164 participants in the NPH insulin group experienced a NFMI (1 study, 495 participants; low-certainty evidence). No study reported NFS. A total of 165/2094 participants (7.9%) in the insulin detemir group compared with 102/1238 participants (8.2%) in the NPH insulin group experienced SAEs (RR 0.95, 95% CI 0.75 to 1.21; 9 studies, 3332 participants; moderate-certainty evidence). Severe nocturnal hypoglycaemia was observed in 70/1823 participants (3.8%) in the insulin detemir group compared with 60/1102 participants (5.4%) in the NPH insulin group (RR 0.67, 95% CI 0.39 to 1.17; 7 studies, 2925 participants; moderate-certainty evidence). The MD in HbA1c comparing insulin detemir with NPH insulin was 0.01%, 95% CI -0.1 to 0.1; 8 studies, 3122 participants; moderate-certainty evidence. Insulin glargine versus NPH insulin (9 RCTs): one adult died in the NPH insulin group (Peto OR 0.14, 95% CI 0.00 to 6.98; 8 studies, 2175 participants; moderate-certainty evidence). Four studies with 1013 participants reported QoL showing no true beneficial effect or harmful effect for either intervention (low-certainty evidence). Severe hypoglycaemia was observed in 122/1191 participants (10.2%) in the insulin glargine group compared with 145/1159 participants (12.5%) in the NPH insulin group (RR 0.84, 95% CI 0.67 to 1.04; 9 studies, 2350 participants; moderate-certainty evidence). No participant experienced a NFMI and one participant in the NPH insulin group experienced a NFS in the single study reporting this outcome (585 participants; low-certainty evidence). A total of 109/1131 participants (9.6%) in the insulin glargine group compared with 110/1098 participants (10.0%) in the NPH insulin group experienced SAEs (RR 1.08, 95% CI 0.63 to 1.84; 8 studies, 2229 participants; moderate-certainty evidence). Severe nocturnal hypoglycaemia was observed in 69/938 participants (7.4%) in the insulin glargine group compared with 83/955 participants (8.7%) in the NPH insulin group (RR 0.83, 95% CI 0.62 to 1.12; 6 studies, 1893 participants; moderate-certainty evidence). The MD in HbA1c comparing insulin glargine with NPH insulin was 0.02%, 95% CI -0.1 to 0.1; 9 studies, 2285 participants; moderate-certainty evidence. Insulin detemir versus insulin glargine (2 RCTs),insulin degludec versus insulin detemir (2 RCTs), insulin degludec versus insulin glargine (4 RCTs): there was no evidence of a clinically relevant difference for all main outcomes comparing (ultra-)long-acting insulin analogues with each other. For all outcomes none of the comparisons indicated differences in tests of interaction for children versus adults.

AUTHORS' CONCLUSIONS

Comparing insulin detemir with NPH insulin for T1DM showed lower risk of severe hypoglycaemia in favour of insulin detemir (moderate-certainty evidence). However, the 95% prediction interval indicated inconsistency in this finding. Both insulin detemir and insulin glargine compared with NPH insulin did not show benefits or harms for severe nocturnal hypoglycaemia. For all other main outcomes with overall low risk of bias and comparing insulin analogues with each other, there was no true beneficial or harmful effect for any intervention. Data on patient-important outcomes such as QoL, macrovascular and microvascular diabetic complications were sparse or missing. No clinically relevant differences were found between children and adults.

Association of insulin regimens with severe hypoglycaemia in patients with type 1 diabetes: A Danish case-control study

AIMS

To evaluate the risk of severe hypoglycaemia for patients with Type 1 diabetes (T1D) when exposed to insulin regimens including human insulin only or insulin analogues.

METHODS

A total of 19 896 patients with T1D were extracted from the Danish National Patient Register. Of these, 6379 T1D patients experiencing 1 of more severe hypoglycaemic episodes (total of 17 242 episodes) were matched 1:1 with T1D patients without severe hypoglycaemia. A logistic regression model with last insulin regimen used as exposure was constructed to analyse the effect on severe hypoglycaemia.

RESULTS

People on a basal-bolus regimen with insulin analogues had a reduced risk of severe hypoglycaemia of 39% (odds ratio: 0.61, 95% confidence interval: 0.54-0.68) compared to patients on a basal-bolus human insulin only regimen. Furthermore, patients on a premixed regimen containing an insulin analogue had a 58% (odds ratio: 0.42, 95% confidence interval: 0.36-0.49) reduced risk of severe hypoglycaemia compared to patients on premixed human insulin only.

CONCLUSION

This study indicates that use of a basal-bolus insulin regimen with an insulin analogue is safer with respect to severe hypoglycaemia in patients with T1D than the use of a basal-bolus human insulin only regimen.

Short-acting insulin analogues versus regular human insulin for adult, non-pregnant persons with type 2 diabetes mellitus

BACKGROUND

The use of short-acting insulin analogues (insulin lispro, insulin aspart, insulin glulisine) for adult, non-pregnant people with type 2 diabetes is still controversial, as reflected in many scientific debates.

OBJECTIVES

To assess the effects of short-acting insulin analogues compared to regular human insulin in adult, non-pregnant people with type 2 diabetes mellitus.

SEARCH METHODS

For this update we searched CENTRAL, MEDLINE, Embase, the WHO ICTRP Search Portal, and ClinicalTrials.gov to 31 October 2018. We placed no restrictions on the language of publication.

SELECTION CRITERIA

We included all randomised controlled trials with an intervention duration of at least 24 weeks that compared short-acting insulin analogues to regular human insulin in the treatment of people with type 2 diabetes, who were not pregnant.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias. We assessed dichotomous outcomes by risk ratios (RR), and Peto odds ratios (POR), with 95% confidence intervals (CI). We assessed continuous outcomes by mean differences (MD) with 95% CI. We assessed trials for certainty of the evidence using the GRADE approach.

MAIN RESULTS

We identified 10 trials that fulfilled the inclusion criteria, randomising 2751 participants; 1388 participants were randomised to receive insulin analogues and 1363 participants to receive regular human insulin. The duration of the intervention ranged from 24 to 104 weeks, with a mean of about 41 weeks. The trial populations showed diversity in disease duration, and inclusion and exclusion criteria. None of the trials were blinded, so the risk of performance bias and detection bias, especially for subjective outcomes, such as hypoglycaemia, was high in nine of 10 trials from which we extracted data. Several trials showed inconsistencies in the reporting of methods and results.None of the included trials defined all-cause mortality as a primary outcome. Six trials provided Information on the number of participants who died during the trial, with five deaths out of 1272 participants (0.4%) in the insulin analogue groups and three deaths out of 1247 participants (0.2%) in the regular human insulin groups (Peto OR 1.66, 95% CI 0.41 to 6.64; P = 0.48; moderate-certainty evidence). Six trials, with 2509 participants, assessed severe hypoglycaemia differently, therefore, we could not summarise the results with a meta-analysis. Overall, the incidence of severe hypoglycaemic events was low, and none of the trials showed a clear difference between the two intervention arms (low-certainty evidence).The MD in glycosylated haemoglobin A1c (HbA1c) change was -0.03% (95% CI -0.16 to 0.09; P = 0.60; 9 trials, 2608 participants; low-certainty evidence). The 95% prediction ranged between -0.31% and 0.25%. The MD in the overall number of non-severe hypoglycaemic episodes per participant per month was 0.08 events (95% CI 0.00 to 0.16; P = 0.05; 7 trials, 2667 participants; very low-certainty evidence). The 95% prediction interval ranged between -0.03 and 0.19 events per participant per month. The results provided for nocturnal hypoglycaemic episodes were of questionable validity. Overall, there was no clear difference between the two short-acting insulin analogues and regular human insulin. Two trials assessed health-related quality of life and treatment satisfaction, but we considered the results for both outcomes to be unreliable (very low-certainty evidence).No trial was designed to investigate possible long term effects (all-cause mortality, microvascular or macrovascular complications of diabetes), especially in participants with diabetes-related complications. No trial reported on socioeconomic effects.

AUTHORS' CONCLUSIONS

Our analysis found no clear benefits of short-acting insulin analogues over regular human insulin in people with type 2 diabetes. Overall, the certainty of the evidence was poor and results on patient-relevant outcomes, like all-cause mortality, microvascular or macrovascular complications and severe hypoglycaemic episodes were sparse. Long-term efficacy and safety data are needed to draw conclusions about the effects of short-acting insulin analogues on patient-relevant outcomes.

Comparative evaluation of pharmacokinetics and pharmacodynamics of insulin glargine (Glaritus®) and Lantus® in healthy subjects: a double-blind, randomized clamp study

AIMS

The objective of the study was to compare the pharmacokinetic (PK) and pharmacodynamic (PD) properties of an insulin glargine formulation, Glaritus^® (test) with the innovator's formulation Lantus^® (reference) using the euglycemic clamp technique in a single-dose, double-blind, randomized, two sequences, four-period replicate crossover study in healthy volunteers (n = 40).

METHODS

Subjects received subcutaneous administration of the insulin glargine (0.4 IU/kg) formulation at two occasions for test and reference and a 20% glucose solution was infused at variable rate to maintain euglycemia for 24 h.

RESULTS

Both PK [area under the plasma concentration time curve (AUC_0-24 h) and maximum insulin concentration (C_max)] and PD endpoints [area under glucose infusion rate time curve (_AUCGIR0-24) and maximum glucose infusion rate (GIR_max)] demonstrated bioequivalence of Glaritus to Lantus with the 90% confidence interval of geometric mean ratio of test to reference entirely contained within 0.80-1.25. Both formulations showed equivalent geometric least-square mean LSM value (0.08 nmol/L) for C_max. The geometric LSM AUC_0-24 h value for Glaritus^® (1.09 h nmol/L) was comparable to Lantus (1.05 h nmol/L). Median T_max values were also identical (12 h for both), and median t1/2 values were also equal (18 h for both). For GIR_Tmax, the difference between the means for the two was not statistically significant. No AEs related to study formulations were reported, and both products were well tolerated.

CONCLUSIONS

The test product (Glaritus) was found to be bioequivalent to the reference product (Lantus).

CLINICAL TRIAL REGISTRATION NUMBER

CTRI/2015/06/005890; http://www.ctri.nic.in/ .

Short-acting insulin analogues versus regular human insulin for adults with type 1 diabetes mellitus

BACKGROUND

Short-acting insulin analogue use for people with diabetes is still controversial, as reflected in many scientific debates.

OBJECTIVES

To assess the effects of short-acting insulin analogues versus regular human insulin in adults with type 1 diabetes.

SEARCH METHODS

We carried out the electronic searches through Ovid simultaneously searching the following databases: Ovid MEDLINE(R), Ovid MEDLINE(R) In-Process & Other Non-Indexed Citations, Ovid MEDLINE(R) Daily and Ovid OLDMEDLINE(R) (1946 to 14 April 2015), EMBASE (1988 to 2015, week 15), the Cochrane Central Register of Controlled Trials (CENTRAL; March 2015), ClinicalTrials.gov and the European (EU) Clinical Trials register (both March 2015).

SELECTION CRITERIA

We included all randomised controlled trials with an intervention duration of at least 24 weeks that compared short-acting insulin analogues with regular human insulins in the treatment of adults with type 1 diabetes who were not pregnant.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trials for risk of bias, and resolved differences by consensus. We graded overall study quality using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) instrument. We used random-effects models for the main analyses and presented the results as odds ratios (OR) with 95% confidence intervals (CI) for dichotomous outcomes.

MAIN RESULTS

We identified nine trials that fulfilled the inclusion criteria including 2693 participants. The duration of interventions ranged from 24 to 52 weeks with a mean of about 37 weeks. The participants showed some diversity, mainly with regard to diabetes duration and inclusion/exclusion criteria. The majority of the trials were carried out in the 1990s and participants were recruited from Europe, North America, Africa and Asia. None of the trials was carried out in a blinded manner so that the risk of performance bias, especially for subjective outcomes such as hypoglycaemia, was present in all of the trials. Furthermore, several trials showed inconsistencies in the reporting of methods and results.The mean difference (MD) in glycosylated haemoglobin A1c (HbA1c) was -0.15% (95% CI -0.2% to -0.1%; P value < 0.00001; 2608 participants; 9 trials; low quality evidence) in favour of insulin analogues. The comparison of the risk of severe hypoglycaemia between the two treatment groups showed an OR of 0.89 (95% CI 0.71 to 1.12; P value = 0.31; 2459 participants; 7 trials; very low quality evidence). For overall hypoglycaemia, also taking into account mild forms of hypoglycaemia, the data were generally of low quality, but also did not indicate substantial group differences. Regarding nocturnal severe hypoglycaemic episodes, two trials reported statistically significant effects in favour of the insulin analogue, insulin aspart. However, due to inconsistent reporting in publications and trial reports, the validity of the result remains questionable.We also found no clear evidence for a substantial effect of insulin analogues on health-related quality of life. However, there were few results only based on subgroups of the trial populations. None of the trials reported substantial effects regarding weight gain or any other adverse events. No trial was designed to investigate possible long-term effects (such as all-cause mortality, diabetic complications), in particular in people with diabetes related complications.

AUTHORS' CONCLUSIONS

Our analysis suggests only a minor benefit of short-acting insulin analogues on blood glucose control in people with type 1 diabetes. To make conclusions about the effect of short acting insulin analogues on long-term patient-relevant outcomes, long-term efficacy and safety data are needed.

Glycaemic variability in diabetes: a tool for assessing the quality of glycaemic control and the risk of complications

The routine approach to evaluating the effectiveness of diabetes treatment based on the level of glycated haemoglobin (HbA. 1c) accounts for the average glucose level but does not consider the scope and frequency of its fluctuations. The development of computational methods to analyse glycaemic oscillations has made it possible to propose the concept of glycaemic variability (GV). The interest in research focused on GV increased dramatically after continuous glucose monitoring (CGM) technology was introduced, which provided the opportunity to study in detail the temporal structure of blood glucose curves. Numerous methods for assessing GV proposed over the past five decades characterize glycaemic fluctuations as functions of concentration and time and estimate the risks of hypoglycaemia and hyperglycaemia. Accumulating evidence indicates that GV may serve as a significant predictor of diabetic complications. Prospective studies demonstrate that certain GV parameters have independent significance for predicting diabetic retinopathy, nephropathy and cardiovascular diseases. There is evidence that GV correlates with the severity of atherosclerotic vascular lesions and cardiovascular outcomes in diabetic patients. The mechanisms underlying the relationship between GV and vascular complications are being intensively studied, and recent data show that the effect of GV on vascular walls may be mediated by oxidative stress, chronic inflammation and endothelial dysfunction. Average blood glucose levels and GV are considered independent predictors of hypoglycaemia. Increased GV is associated with impaired hormonal response to hypoglycaemia and is a long-term predictor of hypoglycaemia unawareness. These data allow us to conclude that computational methods for analysing GV in patients with diabetes may serve as a promising tool for personalized assessment of glycaemic control and the risk of vascular complications and hypoglycaemia. Thus, the reduction of GV can be regarded as one of the therapeutic targets to treat diabetes.

Imaging free zinc levels in vivo - what can be learned?

Our ever-expanding knowledge about the role of zinc in biology includes its role in redox modulation, immune response, neurotransmission, reproduction, diabetes, cancer, and Alzheimers disease is galvanizing interest in detecting and monitoring the various forms of Zn(II) in biological systems. This paper reviews reported strategies for detecting and tracking of labile or "free" unchelated Zn(II) in tissues. While different bound structural forms of Zn(II) have been identified and studied in vitro by multiple techniques, very few molecular imaging methods have successfully tracked the ion in vivo. A number of MRI and optical strategies have now been reported for detection of free Zn(II) in cells and tissues but only a few have been applied successfully in vivo. A recent report of a MRI sensor for in vivo tracking of Zn(II) released from pancreatic β-cells during insulin secretion exemplifies the promise of rational design of new Zn(II) sensors for tracking this biologically important ion in vivo. Such studies promise to provide new insights into zinc trafficking in vivo and the critical role of this ion in many human diseases.