Bihormonal fully closed-loop system for the treatment of type 1 diabetes: a real-world multicentre, prospective, single-arm trial in the Netherlands

BACKGROUND

Management of insulin administration for intake of carbohydrates and physical activity can be burdensome for people with type 1 diabetes on hybrid closed-loop systems. Bihormonal fully closed-loop (FCL) systems could help reduce this burden. In this trial, we assessed the long-term performance and safety of a bihormonal FCL system.

METHODS

The FCL system (Inreda AP; Inreda Diabetic, Goor, Netherlands) that uses two hormones (insulin and glucagon) was assessed in a 1 year, multicentre, prospective, single-arm intervention trial in adults with type 1 diabetes. Participants were recruited in eight outpatient clinics in the Netherlands. We included adults with type 1 diabetes aged 18-75 years who had been using flash glucose monitoring or continuous glucose monitors for at least 3 months. Study visits were integrated into standard care, usually every three months, to evaluate glycaemic control, adverse events, and person-reported outcomes. The primary endpoint was time in range (TIR; glucose concentration 3·9-10·0 mmol/L) after 1 year. The study is registered in the Dutch Trial Register, NL9578.

FINDINGS

Between June 1, 2021, and March 2, 2022, we screened 90 individuals and enrolled 82 participants; 78 were included in the analyses. 79 started the intervention and 71 were included in the 12 month analysis. Mean age was 47.7 (SD 12·4) years and 38 (49%) were female participants. The mean preintervention TIR of participants was 55·5% (SD 17·2). After 1 year of FCL treatment, mean TIR was 80·3% (SD 5·4) and median time below range was 1·36% (IQR 0·80-2·11). Questionnaire scores improved on Problem Areas in Diabetes (PAID) from 30·0 (IQR 18·8-41·3) preintervention to 10·0 (IQR 3·8-21·3; p<0·0001) at 12 months and on World Health Organization-Five Well-Being Index (WHO-5) from 60·0 (IQR 44·0-72·0) preintervention to 76·0 (IQR 60·0-80·0; p<0·0001) at 12 months. Five serious adverse events were reported (one cerebellar stroke, two severe hypoglycaemic, and two hyperglycaemic events).

INTERPRETATION

Real-world data obtained in this trial demonstrate that use of the bihormonal FCL system was associated with good glycaemic control in patients who completed 1 year of treatment, and could help relieve these individuals with type 1 diabetes from making treatment decisions and the burden of carbohydrate counting.

FUNDING

Inreda Diabetic.

Transient thyroiditis after parathyroidectomy for tertiary hyperparathyroidism

Thyrotoxicosis due to thyroiditis is predominantly caused by infection or autoimmune disease of the thyroid. Parathyroid surgery however, is a lesser known cause of thyroiditis, due to thyroid manipulation. We treated a patient who developed transient symptomatic thyroiditis following parathyroid surgery for tertiary hyperparathyroidism. Therefore, the differential diagnosis for patients with symptoms after parathyroid surgery should include transient thyroiditis.

Long-term treatment with metformin in type 2 diabetes and vitamin D levels: A post-hoc analysis of a randomized placebo-controlled trial

AIMS

To study the effects of metformin, as compared to placebo, on serum levels of vitamin D (25-hydroxyvitamin D [25(OH)D]) in patients with advanced type 2 diabetes.

MATERIALS AND METHODS

In the HOME trial, a randomized placebo-controlled trial, 390 insulin-treated patients with type 2 diabetes were treated with 850 mg metformin or placebo thrice daily for 52 months. In a post-hoc analysis, we examined changes in the combined levels of 25(OH)D₂ and 25(OH)D₃ at 4 and 16 months during the study.

RESULTS

Mean combined 25(OH)D at baseline was 68.2 nmoL/L (95% confidence interval [CI]: 65.5-71.1). In mixed model analysis, metformin, as compared to placebo, had no effect on 25(OH)D levels during 16 months (coefficient: 1.002 per month, multiplicative model; 95% CI: 0.998-1.006, P = .30). Metformin was associated with a small increase of 25(OH)D₂ (coefficient: 1.012 per month; 95% CI: 1.003-1.021, P = .008). However, 25(OH)D₂ is only a very small fraction (3%) of 25(OH)D. Seasonal variation had the biggest impact on 25(OH)D levels. Vitamin B12 levels were not associated with the levels of 25(OH)D.

CONCLUSION

Metformin had no effect on serum 25(OH)D during 16 months in the setting of a clinical randomized controlled trial in patients with type 2 diabetes. Our results show that metformin doesn't lead to vitamin D deficiency.

A gene variant near ATM affects the response to metformin and metformin plasma levels: a post hoc analysis of an RCT

AIM

To determine the influence of polymorphisms on the effects of metformin on HbA1c, daily dose of insulin and metformin plasma concentration. Methods: In a post hoc analysis of a 4.3 year placebo-controlled randomized trial with 390 patients with Type 2 diabetes already on insulin, we analyzed the influence of polymorphisms in genes coding for ATM and the transporters OCT1 and MATE1. Outcome measures were a combined HbA1c + daily dose of insulin Z score and metformin plasma concentrations.

RESULTS

rs11212617 (ATM) was associated with an improved Z score and a lower metformin plasma concentration. In addition, the major allele of rs2289669 (MATE1) was also associated with an improved Z score.

CONCLUSION

The ATM SNP rs11212617 significantly affected the effect of metformin and metformin plasma concentration. Further research is needed to determine the clinical importance of these findings, in particular the effects on metformin plasma concentration.

Long-term treatment with metformin in type 2 diabetes and methylmalonic acid: Post hoc analysis of a randomized controlled 4.3year trial

AIMS

Metformin treatment is associated with a decrease of serum vitamin B12, but whether this reflects tissue B12 deficiency is controversial. We studied the effects of metformin on serum levels of methylmalonic acid (MMA), a biomarker for tissue B12 deficiency, and on onset or progression of neuropathy.

METHODS

In the HOME trial, 390 insulin-treated patients with type 2 diabetes were treated with metformin or placebo for 52months. In a post hoc analysis, we analyzed the association between metformin, MMA and a validated Neuropathy Score (NPS).

RESULTS

Metformin vs placebo increased MMA at the end of the study (95%CI: 0.019 to 0.055, p=0.001). Mediation analysis showed that the effect of metformin on the NPS consisted of a beneficial effect through lowering HbA1c (-0.020 per gram year) and an adverse effect through increasing MMA (0.042 per gram year), resulting in a non-significant net effect (0.032 per gram year, 95% CI: -0.121 to 0.182, p=0.34).

CONCLUSION

Metformin not only reduces serum levels of B12, but also progressively increases serum MMA. The increase of MMA in metformin users was associated with significant worsening of the NPS. These results provide further support that metformin-related B12 deficiency is clinically relevant. Monitoring of B12 in users of metformin should be considered.

Metformin-associated prevention of weight gain in insulin-treated type 2 diabetic patients cannot be explained by decreased energy intake: A post hoc analysis of a randomized placebo-controlled 4.3-year trial

Metformin prevents weight gain in patients with type 2 diabetes (T2D). However, the mechanisms involved are still unknown. In this post hoc analysis of the HOME trial, we aimed to determine whether metformin affects energy intake. Patients with T2D were treated with 850 mg metformin or received placebo added to insulin (1-3 times daily) for 4.3 years. Dietary intake was assessed at baseline, after 1 year and after 4.3 years, according to the dietary history method. Among the 310 included participants, 179 (93 placebo, 86 metformin) completed all 3 dietary assessments. We found no significant difference in energy intake after 4.3 years between the groups (metformin vs placebo: -31.0 kcal/d; 95% CI, -107.4 to 45.4; F-value, 1.3; df = 415; P = .27). Body weight in placebo users increased significantly more than in metformin-users during 4.3 years (4.9 ± 4.9 vs 1.1 ± 5.2 kg; t test: P ≤ .001). Linear mixed models did not show a significant effect of energy intake as explanation for the difference in weight gain between the groups (F-value, 0.1; df = 1; P = .82). In conclusion, the prevention of weight gain by metformin cannot be explained by reduced energy intake.

Variants in Pharmacokinetic Transporters and Glycemic Response to Metformin: A Metgen Meta-Analysis

Therapeutic response to metformin, a first-line drug for type 2 diabetes (T2D), is highly variable, in part likely due to genetic factors. To date, metformin pharmacogenetic studies have mainly focused on the impact of variants in metformin transporter genes, with inconsistent results. To clarify the significance of these variants in glycemic response to metformin in T2D, we performed a large-scale meta-analysis across the cohorts of the Metformin Genetics Consortium (MetGen). Nine candidate polymorphisms in five transporter genes (organic cation transporter [OCT]1, OCT2, multidrug and toxin extrusion transporter [MATE]1, MATE2-K, and OCTN1) were analyzed in up to 7,968 individuals. None of the variants showed a significant effect on metformin response in the primary analysis, or in the exploratory secondary analyses, when patients were stratified according to possible confounding genotypes or prescribed a daily dose of metformin. Our results suggest that candidate transporter gene variants have little contribution to variability in glycemic response to metformin in T2D.

Variation in the glucose transporter gene SLC2A2 is associated with glycemic response to metformin

Metformin is the first-line antidiabetic drug with over 100 million users worldwide, yet its mechanism of action remains unclear1. Here the Metformin Genetics (MetGen) Consortium reports a three-stage genome wide association study (GWAS), consisting of 13,123 participants of different ancestries. The C-allele of rs8192675 in the intron of SLC2A2, which encodes the facilitated glucose transporter GLUT2, was associated with a 0.17% (p=6.6x10^-14) greater metformin induced HbA1c reduction in 10,577 participants of European ancestry. rs8192675 is the top cis-eQTL for SLC2A2 in 1,226 human liver samples, suggesting a key role for hepatic GLUT2 in regulation of metformin action. In obese individuals C-allele homozygotes at rs8192675 had a 0.33% (3.6mmol/mol) greater absolute HbA1c reduction than T-allele homozygotes.This is about half the effect seen with the addition of a DPP-4 inhibitor, and equates to a dose difference of 550mg of metformin, suggesting rs8192675 as a potential biomarker for stratified medicine.

Preconditioning of rat hearts by adenosine A1 or A3 receptor activation

Our study in rat hearts examined whether activation of adenosine A(1) or A(3) receptors improved functional recovery and reduced apoptosis resulting from low-flow ischemia. Prior to 30 min low-flow ischemia (0.6 ml/min; 6% of baseline flow), Langendorff rat hearts were preconditioned with two 5-min cycles of (a) ischemia (PC; n=7), (b) infusion of 250 nM adenosine A(1) receptor agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA; n=6), or (c) infusion of 50 nM adenosine A(3) receptor agonist N(6)-(3-iodobenzyl)-adenosine-5'-N-methyl-uronamide (IB-MECA; n=8). Recovery of function was improved in PC (71+/-3%), CCPA (68+/-6%) and IB-MECA (68+/-4%) groups compared to control hearts (46+/-5%; P<0.05). Cumulative release of total purines during ischemia-reperfusion was approx. 50% lower in PC, CCPA and IB-MECA groups compared to controls (P<0.05) and was significantly correlated to the percentage functional recovery (R(2)=0.55; P<0.05). The number of cytosolic histone-associated-DNA fragments, a hallmark of apoptosis and measured by Enzyme Linked ImmunoSorbent Assay (ELISA), was small and not different between groups after 30 min reperfusion. However, CCPA (0.6+/-0.1 absorbance units) and MECA (0.7+/-0.1 units; P<0.05 vs. PC) decreased apoptosis after 150 min reperfusion compared to PC (1.4+/-0.3 units) and control (1.2+/-0.1 units) hearts. This study shows that adenosine triggers protection of function in preconditioned rat hearts via both the adenosine A(1) and A(3) receptor. In clinical practice, pharmacological stimulation of adenosine A(3) receptors may be advantageous over adenosine A(1) receptor activation due to a lack of contractile side-effects. In contrast to ischemic preconditioning, pharmacological stimulation of adenosine A(1) or A(3) receptors reduced apoptosis. Furthermore, total purine release may serve as a marker of the degree of functional protection.

Bioactivation of selenocysteine Se-conjugates by a highly purified rat renal cysteine conjugate beta-lyase/glutamine transaminase K

Selenocysteine Se-conjugates have recently been proposed as potential prodrugs to target pharmacologically active selenol compounds to the kidney. Although rat renal cytosol displayed a high activity of beta-elimination activity toward these substrates, the enzymes involved in this activation pathway as yet have not been identified. In the present study, the possible involvement of cysteine conjugate beta-lyase/glutamine transaminase K (beta-lyase/GTK) in cytosolic activity was investigated. To this end, the enzyme kinetics of 15 differentially substituted selenocysteine Se-conjugates and 11 cysteine S-conjugates was determined using highly purified rat renal beta-lyase/GTK. The results demonstrate that most selenocysteine Se-conjugates are beta-eliminated at a very high activity by purified beta-lyase/GTK, implicating an important role of this protein in the previously reported beta-elimination reactions in rat renal cytosol. As indicated by the rapid consumption of alpha-keto-gamma-methiolbutyric acid, purified beta-lyase/GTK also catalyzed transamination reactions, which appeared to even exceed that of beta-elimination. The corresponding sulfur analogs also showed significant transamination but were beta-eliminated at an extremely low rate. Comparison of the obtained enzyme kinetic data of purified beta-lyase/GTK with previously obtained data from rat renal cytosol showed a poor correlation. By determining the activity profiles of cytosolic fractions applied to anion exchange fast protein liquid chromatography and gel filtration chromatography, the involvement of multiple enzymes in the beta-elimination of selenocysteine Se-conjugates in rat renal cytosol was demonstrated. The identity and characteristics of these alternative selenocysteine conjugate beta-lyases, however, remain to be established.

Phenotypic heterogeneity in cultured skin fibroblasts from patients with disorders of peroxisome biogenesis belonging to the same complementation group

We have studied fibroblast cell lines derived from a control subject (cell line 85AD5035F) and three patients clinically described as having the Zellweger syndrome (cell line W78/515), the infantile form of Refsum disease (cell line BOV84AD) and hyperpipecolic acidaemia (cell line GM3605), respectively. The mutant cell lines belonged to the same complementation group. The fibroblasts were cultured under identical conditions and were harvested at different time intervals after reaching confluence. Several peroxisomal parameters were determined. In agreement with previous reports, a lowered enzymic activity of acyl-CoA: dihydroxyacetonephosphate acyltransferase and a decrease in latent catalase clearly distinguished the patient cell lines from the control cell line. However, the cell lines exhibited a phenotypic heterogeneity. This was most strikingly encountered when cells were processed for indirect immunofluorescence microscopy and stained with anti-(catalase). The control cells exhibited a punctate fluorescence, which is indicative of the presence of catalase in peroxisomes. In the mutant cell line W78/515 a diffuse fluorescence was observed, indicative of the presence of catalase in the cytosol. In the other two mutant cell lines a punctate fluorescence was observed in some of the cells. Moreover, clear differences in the extent of proteolytic processing of acyl-CoA oxidase were detected. The mutant cell line BOV84AD displayed a control-like pattern with all molecular forms of acyl-CoA oxidase (72, 52 and 20 kDa) present, whereas in the W78/515 cell line only the 72 kDa component could be visualised. The GM3605 cell line was intermediate in this respect.