A Novel Dual-Hormone Insulin-and-Pramlintide Artificial Pancreas for Type 1 Diabetes: A Randomized Controlled Crossover Trial

OBJECTIVE

The rapid insulin-alone artificial pancreas improves glycemia in type 1 diabetes but daytime control remains suboptimal. We propose two novel dual-hormone artificial pancreas systems.

RESEARCH DESIGN AND METHODS

We conducted a randomized crossover trial comparing a rapid insulin-alone artificial pancreas with rapid insulin-and-pramlintide and with regular insulin-and-pramlintide artificial pancreas systems in adults with type 1 diabetes. Participants were assigned to the interventions in random order during three 24-h inpatient visits. Each visit was preceded by an outpatient hormonal open-loop run-in period of 10-14 days. The dual-hormone artificial pancreas delivered pramlintide in a basal-bolus manner, using a novel dosing algorithm, with a fixed ratio relative to insulin. The primary outcome was time in the range 3.9-10.0 mmol/L.

RESULTS

Compared with the rapid insulin-alone artificial pancreas system, the rapid insulin-and-pramlintide system increased the time in range from 74% (SD 18%) to 84% (13%) (P = 0.0014), whereas the regular insulin-and-pramlintide system did not change the time in range (69% [19%]; P = 0.22). The increased time in range with the rapid insulin-and-pramlintide system was due to improved daytime control (daytime time in range increased from 63% [23%] to 78% [16%], P = 0.0004). There were 11 (1 per 2.5 days) hypoglycemic events (<3.3 mmol/L with symptoms or <3.0 mmol/L irrespective of symptoms) with the rapid insulin-alone system, compared with 12 (1 per 2.3 days) and 18 (1 per 1.4 days) with the rapid and regular insulin-and-pramlintide systems, respectively. Gastrointestinal symptoms were reported after 0% (0 of 112) of meals with the rapid insulin-alone system, compared with 6% (6 of 108) and 11% (11 of 104) with the rapid and regular insulin-and-pramlintide systems, respectively; none of the symptoms were severe.

CONCLUSIONS

A novel rapid insulin-and-pramlintide artificial pancreas improves glucose control compared with a rapid insulin-alone artificial pancreas (ClinicalTrials.gov number NCT02814123).

Accuracy of FreeStyle Libre in Adults with Type 1 Diabetes: The Effect of Sensor Age

Background: FreeStyle Libre is a factory-calibrated continuous 14-day glucose sensor. Little is known about the accuracy of FreeStyle Libre as a function of sensor age. Methods: We assessed the accuracy of FreeStyle Libre in 14 adults with type 1 diabetes. Each study participant attended our research facility for two or three 24-h visits, during which they wore a FreeStyle Libre aged 0-1 day, 5-7 days, or 13-14 days. Plasma glucose levels were measured every 10-30 min using YSI2300 STAT Plus Analyser. Participants also wore Dexcom G5^® glucose sensor aged 1-2 days. We assessed sensors' accuracy using mean absolute relative difference (MARD) between FreeStyle Libre, the Dexcom G5 sensor, and plasma glucose. Results: We had 1930 pairs of FreeStyle Libre sensor-plasma glucose measurements, collected from 36 FreeStyle Libre sensors, 18 of which were sensors aged 0-1 day, 9 were sensors aged 5-7 days, and 9 were sensors aged 13-14 days. The mean and median MARD for FreeStyle Libre sensors aged 0-1 days were 14.5% and 11.2%, respectively, and for sensors aged 13-14 days were 14.7% and 11.2%, respectively, but for sensors aged 5-7 days were 7.8% and 6.6%, respectively (P = 0.03 vs. sensors aged 0-1 days, and P = 0.06 vs. sensors aged 13-14 days). The percentage of points falling in the potentially dangerous zones C, D, or E in Clarke's error grid analysis were 1.9% for FreeStyle Libre sensors aged 0-1 day, 0.2% for sensors aged 5-7 days, and 0.4% for sensors aged 13-14 days. The overall accuracy of FreeStyle Libre and Dexcom G5 sensor was the same (mean MARD 12.8% and 12.5%, respectively; P = 0.57). Conclusions: FreeStyle Libre's accuracy is adequate during its entire lifetime but is least accurate during its first and last days. ClinicalTrials.gov Identifier: NCT02814123.

Contributions of natural arsenic sources to surface waters on a high grade arsenic-geochemical anomaly (French Massif Central)

The subwatershed studied drains a non-exploited area of the St-Yrieix-la-Perche gold mining district (French Massif Central) and it is located on an arsenic (As) geochemical anomaly. In this context, it is important to know the geochemical processes involved in the transfer of As from solid environmental compartments to the aquatic system. The stream showed a temporal variation of dissolved As (As(d)) content from 69.4 μg.L(-1) in the low flow period to 7.5 μg.L(-1) in the high flow period. Upstream, ground- and wetland waters had As(d) concentrations up to 215 and 169 μg.L(-1), respectively. The main representative As sources were determined at the subwatershed scale with in-situ monitoring of major and trace element contents in different waters and single extraction experiments. The As sources to stream water could be regrouped into two components: (i) one As-rich group (mainly in the low flow period) with groundwater, gallery exploration outlet waters and wetland waters, and (ii) one As-poor group (mainly in the high flow period) with rainwaters and soil solutions. In the soil profile, As(d) showed a significant decrease from 52.4 μg.L(-1) in the 0-5 cm superficial soil horizon to 14.4 μg.L(-1) in the 135-165 cm deep soil horizon. This decrease may be related to pedogenic processes and suggests an evolution of As-bearing phase stability through the soil profile. Quantification of As(d) fluxes at the subwatershed scale showed that groundwater was the major input (>80%) of As(d) to surface water. Moreover, natural weathering of the As-rich solid phases showed an impact on the As release, mainly from superficial soil horizons with runoff contributing about 5% to As input in surface water.

Deconvolution of trace element (As, Cr, Mo, Th, U) sources and pathways to surface waters of a gold mining-influenced watershed

The Upper Isle River (SW France) drains the second most productive gold-mining district of France. A high resolution survey during one hydrological year of As, Cl(-), Cr, Fe, Mn, Mo, SO(4)(2-), Th and U dissolved concentrations in surface water aimed to better understand pathways of trace element export to the river system downstream from the mining district. Dissolved concentrations of As (up to 35000 ng/L) and Mo (up to 292 ng/L) were about 3-fold higher than the regional dissolved background and showed a negative logarithmic relation with discharge. Dissolved concentrations of Cr (up to 483 ng/L), Th (up to 48 ng/L) and U (up to 184 ng/L) increased with discharge. Geochemical relationships between molar ratios in surface water, geochemical background as well as rain- and groundwater data were combined. The contrasting behavior of distinct element groups was explained by a scenario involving three seasonal components: (i) The high flow component is poorly concentrated in As and Mo but highly concentrated in Cr, Th, U. This has been attributed to diffuse sources such as water-soil interactions, atmospheric inputs, bedrock and bed sediment weathering. Although this component probably also includes a contribution by weathering of sulfide veins, this signal is masked by dilution. (ii) One low flow component presents high SO(4)(2-), Fe, As and Mo and moderate Cr, Th and U concentrations. This component has been attributed to point sources such as mine gallery effluents, mining waste weathering and groundwater inputs from natural and/or mining-induced sulfide oxidation in the ore deposit. (iii) A second low flow component showing high As plus Mo concentrations associated with very low SO(4)(2-), Fe, Cr, Th and U concentrations, probably reflects trace element scavenging by ferric oxyhydroxide formation in the adjacent aquifer. This is supported by the decrease of Fe, Cr, Th and U in surface waters. Flux estimates suggest contrasting element-specific impacts on annual dissolved fluxes. Runoff may account for the major part of annual dissolved As, Mo, Th and U fluxes in the Upper Isle River. Inputs related to sulfide oxidation respectively contributed approximately 30% and approximately 24% to annual As and Mo fluxes. The formation of ferric oxyhydroxides strongly retained Cr, Th and U during the low flow, limiting their dissolved concentrations in surface waters. If this process may eventually decrease As mobility, its impact on dissolved As concentrations in surface water may be limited or/and counterbalanced by As release during sulfide oxidation.