Acceptability and experiences of real-time continuous glucose monitoring in adults with type 2 diabetes using insulin: a qualitative study.

Aims: To explore the lived experiences of initiating real-time continuous glucose monitoring (rt-CGM) use in individuals with type 2 diabetes using insulin. Methods: Twelve semi-structured interviews were conducted amongst individuals with type 2 diabetes taking insulin who were enrolled in the 2GO-CGM randomised controlled trial and had completed 3 months of rtCGM. Interviews were transcribed verbatim and analysed to identify common themes regarding their experiences. Results: The interviews revealed three key themes: i) rtCGM as a facilitator of improved health behaviours; ii) the acceptability of rtCGM systems compared to capillary blood glucose testing; and iii) barriers to the continual usage of rtCGM technology - including: connection difficulties, longevity of the sensors, and local cutaneous reactions to the sensor adhesive. Conclusion: Adults on insulin with type 2 diabetes find rtCGM systems widely acceptable, and easier to engage with than traditional self-monitoring of capillary blood glucose. Supplementary Information: The online version contains supplementary material available at 10.1007/s40200-024-01403-9.

Protocol for a prospective, multicenter, parallel-group, open-label randomized controlled trial comparing standard care with Closed lOoP In chiLdren and yOuth with Type 1 diabetes and high-risk glycemic control: the CO-PILOT trial.

Purpose: Advanced hybrid closed loop (AHCL) systems have the potential to improve glycemia and reduce burden for people with type 1 diabetes (T1D). Children and youth, who are at particular risk for out-of-target glycemia, may have the most to gain from AHCL. However, no randomized controlled trial (RCT) specifically targeting this age group with very high HbA1c has previously been attempted. Therefore, the CO-PILOT trial (Closed lOoP In chiLdren and yOuth with Type 1 diabetes and high-risk glycemic control) aims to evaluate the efficacy and safety of AHCL in this group. Methods: A prospective, multicenter, parallel-group, open-label RCT, comparing MiniMed™ 780G AHCL to standard care (multiple daily injections or continuous subcutaneous insulin infusion). Eighty participants aged 7-25 years with T1D, a current HbA1c ≥ 8.5% (69 mmol/mol), and naïve to automated insulin delivery will be randomly allocated to AHCL or control (standard care) for 13 weeks. The primary outcome is change in HbA1c between baseline and 13 weeks. Secondary outcomes include standard continuous glucose monitor glycemic metrics, psychosocial factors, sleep, platform performance, safety, and user experience. This RCT will be followed by a continuation phase where the control arm crosses over to AHCL and all participants use AHCL for a further 39 weeks to assess longer term outcomes. Conclusion: This study will evaluate the efficacy and safety of AHCL in this population and has the potential to demonstrate that AHCL is the gold standard for children and youth with T1D experiencing out-of-target glucose control and considerable diabetes burden. Trial registration: This trial was prospectively registered with the Australian New Zealand Clinical Trials Registry on 14 November 2022 (ACTRN12622001454763) and the World Health Organization International Clinical Trials Registry Platform (Universal Trial Number U1111-1284-8452). Supplementary Information: The online version contains supplementary material available at 10.1007/s40200-024-01397-4.

Real time continuous glucose monitoring in high-risk people with insulin-requiring type 2 diabetes: A randomised controlled trial.

AIMS: To investigate the impact of real-time continuous glucose monitoring (rtCGM) on glycaemia in a predominantly indigenous (Maori) population of adults with insulin-requiring type 2 diabetes (T2D) in New Zealand. METHODS: Twelve-week, multicentre randomised controlled trial (RCT) of adults with T2D using ≥0.2 units/kg/day of insulin and elevated glycated haemoglobin (HbA1c) ≥64 mmol/mol (8.0%). Following a 2-week blinded CGM run-in phase, participants were randomised to rtCGM or control (self-monitoring blood glucose [SMBG]). The primary outcome was time in the target glucose range (3.9-10 mmol/L; TIR) during weeks 10-12, with data collected by blinded rtCGM in the control group. RESULTS: Sixty-seven participants entered the RCT phase (54% Maori, 57% female), median age 53 (range 16-70 years), HbA1c 85 (IQR 74, 94) mmol/mol (9.9 [IQR 8.9, 10.8]%), body mass index (36.7 ± 7.7 kg/m2). Mean (±SD) TIR increased from 37 (24)% to 53 (24)% [Δ 13%; 95% CI 4.2 to 22; P = 0.007] in the rtCGM group but did not change in the SMBG group [45 (21)% to 45 (25)%, Δ 2.5%, 95% CI -6.1 to 11, P = 0.84]. Baseline-adjusted between-group difference in TIR was 10.4% [95% CI -0.9 to 21.7; P = 0.070]. Mean HbA1c (±SD) decreased in both groups from 85 (18) mmol/mol (10.0 [1.7]%) to 64 (16) mmol/mol (8.0 [1.4]%) in the rtCGM arm and from 81 (12) mmol/mol (9.6 [1.1]%) to 65 (13) mmol/mol (8.1 [1.2]%) in the SMBG arm (P < 0.001 for both). There were no severe hypoglycaemic or ketoacidosis events in either group. CONCLUSIONS: Real-time CGM use in a supportive treat-to-target model of care likely improves glycaemia in a population with insulin-treated T2D and elevated HbA1c.

Do-it-yourself continuous glucose monitoring in people aged 16 to 69 years with type 1 diabetes: A qualitative study.

AIMS: In many countries, real-time continuous glucose monitoring (rt-CGM) is not funded, and cost presents a barrier to access. A do-it-yourself conversion of intermittently scanned CGM (DIY-CGM) is a cheaper alternative. This qualitative study aimed to explore user experiences with DIY-CGM in people aged 16 to 69 years with type 1 diabetes (T1D). METHODS: Convenience sampling was used to recruit participants for semi-structured virtual interviews exploring experiences of DIY-CGM use. Participants were recruited after completing the intervention arm of a crossover randomised controlled trial that evaluated DIY-CGM versus intermittently scanned CGM (isCGM). Participants were previously naive to DIY-CGM and rt-CGM but not isCGM. The DIY-CGM intervention consisted of a Bluetooth bridge connected to isCGM, adding rt-CGM functionality over 8 weeks. Interviews were transcribed, then thematic analysis was performed. RESULTS: Interviews were with 12 people aged 16 to 65 years, with T1D: mean age ± SD 43 ± 14 years; baseline mean HbA1c ± SD 60 mmol/mol ± 9.9 (7.6 ± 0.9%) and time in range 59.8% ± 14.8%. Participants perceived that using DIY-CGM improved both glycaemic control and aspects of quality of life. Alarm and trend functionality allowed participants to perceive reduced glycaemic variability overnight and following meals. The addition of a smartwatch increased discrete access to glucose information. There was a high degree of trust in DIY-CGM. Challenges while using DIY-CGM included signal loss during vigorous exercise, alarm fatigue and short battery life. CONCLUSIONS: This study suggests that for users, DIY-CGM appears to be an acceptable alternative method of rt-CGM.

Glucose and Psychosocial Outcomes 12 Months Following Transition from Multiple Daily Injections to Advanced Hybrid Closed Loop in Youth with Type 1 Diabetes and Suboptimal Glycemia.

Objective: To investigate 12-month glycemic and psychosocial changes following transition from multiple daily injections (MDI) to advanced hybrid closed-loop (AHCL) therapy in youth (aged 13-25 years) with type 1 diabetes and suboptimal glycemia (glycated hemoglobin [HbA1c] ≥8.5% [69 mmol/mol]). Research Design and Methods: Prospective, single arm, dual-center study in 20 participants. Extension phase outcomes reported after 12 months, including HbA1c, time in glycemic ranges, AHCL system performance, and psychosocial questionnaires assessing quality of life, diabetes treatment, and sleep. Results: After 12 months, 19 out of 20 participants continued to use AHCL. Average time-in-range 70-180 mg/dL (3.9-10.0 mmol/L) improved from 27.6% ± 13.2% to 62.5% ± 11.4%. This translated to an average 2.5 percentage-point (27.1 mmol/mol) improvement in HbA1c from 10.5% ± 2.1% (91.2 mmol/mol) at baseline to 8.0% ± 0.9% (64.1 mmol/mol) at 12 months. Psychosocial questionnaires and very high HbA1c at study entry indicated significant diabetes-associated burden for both individuals and parents. After 12 months, improvements were observed in general and diabetes-specific health-related quality of life, as well as in diabetes treatment satisfaction. Safety data were reassuring with a diabetic ketoacidosis rate of 0.15 per participant-year after 12 months of AHCL (compared to 0.25 per participant-year in the 12 months before the study). Conclusions: After 12 months of AHCL usage, this study highlights the potential for substantial and sustained glycemic and psychosocial improvements among individuals experiencing considerable diabetes burden and suboptimal glycemia, following their switch from MDI to AHCL.

Associations between type 1 diabetes and educational outcomes: an Aotearoa/New Zealand nationwide birth cohort study using the Integrated Data Infrastructure.

AIMS/HYPOTHESIS: Type 1 diabetes is one of the most common chronic diseases of childhood. It is hypothesised that the metabolic and psychosocial consequences of type 1 diabetes may affect educational outcomes; however, existing literature presents conflicting results. This study aimed to assess whether educational outcomes differ for young people with and without type 1 diabetes in Aotearoa/New Zealand (NZ). METHODS: This was a nationwide 9 year birth cohort study of all people born in NZ from 1993 to 2001 using linked administrative data held within the Integrated Data Infrastructure, a national research database containing linked health and non-health data. Educational outcomes of high school attainment, high school attendance and university enrolment were measured from age 13 years until 20 years. Generalised linear regression models with log link and Gaussian distributions were used to compare educational outcomes between those with and those without type 1 diabetes, adjusting for sociodemographic and maternal characteristics. RESULTS: Of the 442,320 children in the birth cohort, type 1 diabetes was identified in 2058 (0.47%) (mean [SD] age of type 1 diabetes diagnosis 7.7 [3.4] years). Educational outcomes were significantly lower for children with type 1 diabetes than for those without type 1 diabetes, including for any high school qualification (RR 0.97 [95% CI 0.95, 0.99]), university entrance-level high school attainment (RR 0.88 [95% CI 0.84, 0.92]), regular high school attendance (RR 0.91 [95% CI 0.85, 0.97]) and university enrolment (RR 0.93 [95% CI 0.88, 0.98]), even after adjusting for sociodemographic and maternal factors. In addition, educational outcomes were substantially lower for those with post type 1 diabetes diagnosis hospitalisations for diabetic ketoacidosis and hypoglycaemia. CONCLUSIONS/INTERPRETATION: In this whole NZ birth cohort study, type 1 diabetes was associated with lower educational outcomes spanning secondary school and into university enrolment. Ongoing efforts to support students with type 1 diabetes are needed, particularly for those with a greater risk profile.

Study protocol: glycaemic outcomes in people with type 2 diabetes initiating continuous glucose monitoring: the 2GO-CGM study.

Purpose: Improving glycaemic control in type 2 diabetes (T2D) is essential to reducing social and health-economic burden of diabetes-related complications. Continuous glucose monitoring (CGM) has been established as beneficial in improving glycaemic control and reducing hypoglycaemia in people with type 1 diabetes, however data in T2D is limited. This study has been designed to assess the effect of initiating real-time CGM (rtCGM) on glycaemic control in a high-risk population of adults with T2D. Secondary objectives are to assess the cost-effectiveness and safety of rtCGM, and the effects of rtCGM on diet/lifestyle and the burden of diabetic complications, including cardiovascular risk. Methods: This multicentre randomised controlled trial (RCT) will be conducted at three sites in New Zealand (Waikato, Christchurch and Dunedin). Eighty adults with T2D on insulin with suboptimal glycaemic control (HbA1c > 8.0% or 64 mmol/mol) will be randomised 1:1 to rtCGM or routine care with self-monitoring of blood glucose levels (SMBG) for three months. This intervention phase will be followed by a three-month continuation phase where SMBG group crossover to use rtCGM. Participants will then be invited to join the extension phase with continued use of rtCGM for a further 12 months. During the extension phase, both groups will independently titrate their insulin under the remote supervision of prescribing diabetes nurse specialists following an insulin titration algorithm. The primary outcome of the study is time in target glucose range (3.9-10 mmol/L or 70-180 mg/dL; TIR). Secondary outcomes include CGM metrics as per consensus statement recommendations, and HbA1c. Additional planned analyses include cardiovascular risk profile, incremental cost-effectiveness analyses, dietary patterns, and qualitative analyses. Trial registration number: The trial was registered with the Australian New Zealand Clinical Trials Registry (ACTRN12621000889853) on 8 July 2021 and the World Health Organisation International Clinical Trial Registry Platform (Universal Trial Number U1111-1264-5822).

Effects of 12-Week Freestyle Libre 2.0 in Children with Type 1 Diabetes and Elevated HbA1c: A Multicenter Randomized Controlled Trial.

Objective: To investigate whether intermittently scanned continuous glucose monitoring (isCGM) reduced glycated hemoglobin (HbA1c) compared with capillary self-monitored capillary blood glucose (SMBG) in children with type 1 diabetes (T1D) and elevated glycemic control. Research Design and Methods: This multicenter 12-week 1:1 randomized, controlled, parallel-arm trial included 100 participants with established T1D aged 4-13 years (mean 10.9 ± 2.3 years) naive to isCGM and with elevated HbA1c 7.5%-12.2% [58-110 mmol/mol] [mean HbA1c was 9.05 (1.3)%] [75.4 (13.9) mmol/mol]. Participants were allocated to 12-week intervention (isCGM; FreeStyle Libre 2.0; Abbott Diabetes Care, Witney, United Kingdom) (n = 49) or control (SMBG; n = 51). The primary outcome was the difference in change of HbA1c from baseline to 12 weeks. Results: There was no evidence of a difference between groups for change in HbA1c at 12 weeks (0.23 [95% confidence interval; CI: -0.21 to 0.67], P = 0.3). However, glucose-monitoring frequency increased with isCGM +4.89/day (95% CI 2.97-6.81; P < 0.001). Percent time below range (TBR) <3.9 mmol/L (70-180 mg/dL) was reduced with isCGM -6.4% (10.6 to -4.2); P < 0.001. There were no differences in within group changes for Parent or Child scores of psychosocial outcomes at 12 weeks. Conclusions: For children aged 4-13 years with elevated Hba1c isCGM led to improvements in glucose testing frequency and reduced time below range. However, isCGM did not translate into reducing Hba1c or psychosocial outcomes compared to usual care over 12-weeks. The trial is registered within the Australian New Zealand Trial Registry on February 19, 2020 (ACTRN12620000190909p; ANZCTR.org.au) and the World Health Organization International Clinical Trials Registry Platform (Universal Trial Number U1111-1237-0090).

Knowledge, safety, and impact of alcohol consumption in young adults with type 1 diabetes mellitus: a qualitative study.

PURPOSE: To explore the lived experiences of alcohol consumption among young adults with type 1 diabetes. METHODS: Fourteen semi-structured interviews were conducted amongst young adults aged between 18 and 25 years, inclusive, with type 1 diabetes and experience consuming alcohol. Interviews were transcribed verbatim and analysed to identify common themes regarding their experiences. RESULTS: The interviews confirmed that young adults with type 1 diabetes engage in social, and occasionally excessive, drinking behaviour. Furthermore, the interviews revealed four key themes: (i) Several sources contribute to a widely inconsistent understanding of the impact and management of alcohol consumption; (ii) Perceived inconvenience of maintaining healthy glycaemic control whilst drinking socially; (iii) Engagement in proactive strategies for harm reduction occurred when convenient; and (iv) Impact of modern diabetes technology in overcoming previous burdens and promoting glycaemic safety. CONCLUSION: Young adults with type 1 diabetes continue to need anticipatory education surrounding safe alcohol consumption and behaviours, as well as ongoing support and encouragement to ensure engagement with traditional self-management tasks. Significant alcohol-diabetes related safety issues, particularly hypoglycaemia do occur, and were captured within this small sample and study. Diabetes technology has an important complementary role along with education and tailored support strategies to support health and safe glucose control during alcohol consumption.

Impact of Advanced Hybrid Closed Loop on Youth With High-Risk Type 1 Diabetes Using Multiple Daily Injections.

OBJECTIVE: To evaluate glycemic outcomes in youth (aged 13-25 years) with type 1 diabetes and high-risk glycemic control (HbA1c ≥8.5% [69 mmol/mol]) on multiple daily injection (MDI) therapy after transitioning to advanced hybrid closed loop (AHCL) therapy. RESEARCH DESIGN AND METHODS: This prospective, 3-month, single-arm, dual-center study enrolled 20 participants, and all completed the study. RESULTS: HbA1c decreased from 10.5 ± 2.1% (91.2 ± 22.8 mmol/mol) at baseline to 7.6 ± 1.1% (59.7 ± 11.9 mmol/mol), and time spent in target range 70-180 mg/dL (3.9-10.0 mmol/L) increased from 27.6 ± 13.2% at baseline to 66.5 ± 9.8% after 3 months of AHCL. Two episodes of diabetic ketoacidosis attributed to infusion set failure occurred. CONCLUSIONS: AHCL has the potential to improve suboptimal glycemia in youth with type 1 diabetes previously on MDI therapy.

A comparison of FreeStyle Libre 2 to self-monitoring of blood glucose in children with type 1 diabetes and sub-optimal glycaemic control: a 12-week randomised controlled trial protocol.

PURPOSE: Frequent glucose monitoring is necessary for optimal glycaemic control. Second-generation intermittently scanned glucose monitoring (isCGM) systems inform users of out-of-target glucose levels and may reduce monitoring burden. We aim to compare FreeStyle Libre 2 (Abbott Diabetes Care, Witney, U.K.) to self-monitoring of blood glucose in children with type 1 diabetes and sub-optimal glycaemic control. METHODS: This open-label randomised controlled trial will enrol 100 children (4-13 years inclusive, diagnosis of type 1 diabetes ≥ 6 months, HbA1c 58-110 mmol/mol [7.5-12.2%]), from 5 New Zealand diabetes centres. Following 2 weeks of blinded sensor wear, children will be randomised 1:1 to control or intervention arms. The intervention (duration 12 weeks) includes second-generation isCGM (FreeStyle Libre 2) and education on using interstitial glucose data to manage diabetes. The control group will continue self-monitoring blood glucose. The primary outcome is the difference in glycaemic control (measured as HbA1c) between groups at 12 weeks. Pre-specified secondary outcomes include change in glucose monitoring frequency, glycaemic control metrics and psychosocial outcomes at 12 weeks as well as isCGM acceptability. DISCUSSION: This research will investigate the effectiveness of the second-generation isCGM to promote recommended glycaemic control. The results of this trial may have important implications for including this new technology in the management of children with type 1 diabetes. TRIAL REGISTRATION: This trial was prospectively registered with the Australian New Zealand Clinical Trials Registry on 19 February 2020 (ACTRN12620000190909p) and the World Health Organization International Clinical Trials Registry Platform (Universal Trial Number U1111-1237-0090).

Study protocol: Safety and efficacy of smart watch integrated do-it-yourself continuous glucose monitoring in adults with Type 1 diabetes, a randomised controlled trial.

PURPOSE: Type 1 diabetes (T1D) management requires regular monitoring of glucose levels and judicious therapeutic administration of insulin to prevent both microvascular and macrovascular complications. Few people with diabetes are able to sustain the self-monitored blood glucose measurements needed for optimal care, and those that do, typically experience significant diabetes-related distress. Both intermittently scanned continuous glucose monitoring (isCGM) and continuous glucose monitoring (CGM) offer alternatives to reduce the overall burden, but both still have limitations. Given the expense of CGM, smart watch integrated do-it-yourself (DIY)-CGM has been developed as an alternative to commercial isCGM and CGM technologies. This study has been designed to evaluate the clinical efficacy of smart watch integrated DIY-CGM compared with isCGM in adults with T1D. METHODS: This multicentre, randomised, crossover study will be conducted in New Zealand and aims to recruit 60 adults with established T1D who currently use isCGM. DIY-CGM will be compared to usual care with isCGM. Participants will be randomised to either arm of the study for 8 weeks followed by a 4-week washout period before crossing over to the other study arm for a further 8 weeks. The primary endpoint is glucose time in range (TIR) defined as percentage of time interstitial glucose is spent between 3.9 to 10 mmol/L for the entire intervention period. Secondary endpoints include diabetes-related quality of life, distress, and sleep quality in participants and their partners. DISCUSSION: The results of this study will provide clinical trial data regarding smart watch integrated DIY-CGM versus isCGM for improving glycaemic control in adults with T1D, and also report a variety of key secondary outcomes, including changes in subjective outcome measures for both people with diabetes and their partners. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry (ACTRN12621000648820,31 May 2021); World Health Organisation International Clinical Trial Registry Platform (U1111-1262-2784, 3rd December 2020).

Central signalling cross-talk between insulin and leptin in glucose and energy homeostasis.

Energy homeostasis is controlled by an intricate regulatory system centred in the brain. The peripheral adiposity signals insulin and leptin play a crucial role in this system by informing the brain of the energy status of the body and mediating their catabolic effects through signal transduction in hypothalamic areas that control food intake, energy expenditure and glucose metabolism. Disruptions of insulin and leptin signalling can result in diabetes and obesity. The central signalling cross-talk between insulin and leptin is essential for maintenance of normal healthy energy homeostasis. An important role of leptin in glucoregulation has been revealed. Typically regarded as being controlled by insulin, the control of glucose homeostasis critically depends on functional leptin action. Leptin, on the other hand, is able to lower glucose levels in the absence of insulin, although insulin is necessary for long-term stabilisation of euglycaemia. Evidence from rodent models and human patients suggests that leptin improves insulin sensitivity in type 1 diabetes. The signalling cross-talk between insulin and leptin is likely conveyed by the WNT/ß-catenin pathway. Leptin activates WNT/ß-catenin signalling, leading to inhibition of glycogen synthase kinase-3ß, a key inhibitor of insulin action, thereby facilitating improved insulin signal transduction and sensitisation of insulin action. Interestingly, insights into the roles of insulin and leptin in insects and fish indicate that leptin may have initially evolved as a glucoregulatory hormone and that its anorexigenic and body weight regulatory function was acquired throughout evolution. Furthermore, the regulation of both central and peripheral control of energy homeostasis is tightly controlled by the circadian clock, allowing adaptation of homeostatic processes to environmental cues.

Docosahexaenoic acid prevents palmitate-induced insulin-dependent impairments of neuronal health.

The importance of fatty acids (FAs) for healthy brain development and function has become more evident in the past decades. However, most studies focus on the hypothalamus as an important FA-sensing brain region involved in energy homeostasis. Less work has been done to evaluate the effects of FAs on brain regions such as the hippocampus or cortex, two important centres of learning, memory formation, and cognition. Furthermore, the mechanisms of how FAs modulate the neuronal development and function are incompletely understood. Therefore, this study examined the effects of the saturated FA palmitic acid (PA) and the polyunsaturated FA docosahexaenoic acid (DHA) on primary hippocampal and cortical cultures isolated from P0/P1 Sprague Dawley rat pups. Exposure to PA, but not DHA, resulted in severe morphological changes in primary neurons such as cell body swelling, axonal and dendritic blebbing, and a reduction in synaptic innervation, compromising healthy cell function and excitability. Pharmacological assessment revealed that the PA-mediated alterations were caused by overactivation of neuronal insulin signaling, demonstrated by insulin stimulation and phosphoinositide 3-kinase inhibition. Remarkably, co-exposure to DHA prevented all PA-induced morphological changes. This work provides new insights into how FAs can affect the cytoskeletal rearrangements and neuronal function via modulation of insulin signaling.

Hypothalamic leptin sensitivity and health benefits of time-restricted feeding are dependent on the time of day in male mice.

Synchronization between biologic clocks and metabolism is crucial for most species. Here, we examined the ability of leptin, important in the control of energy metabolism, to induce leptin signaling at the molecular as well as the behavioral level throughout the 24-h day in mice fed either a control or a high-fat diet (HFD). Furthermore, we investigated the effects of time-restricted feeding (TRF; a limitation of HFD access to 6 h each day) on energy metabolism during different periods throughout the 24-h day. In control mice, molecular leptin sensitivity was highest at zeitgeber time (ZT)0 (lights on), declining during the light phase, and increasing during the dark phase. Surprisingly, leptin resistance in HFD-fed mice was only present from the middle of the dark to the middle of the light period. Specifically, when TRF occurred from ZT21 to ZT3 (when leptin resistance in HFD-fed mice was most profound), it resulted in a disruption of the daily rhythms of locomotor activity and energy expenditure and in increased plasma insulin levels compared with other TRF periods. These data provide evidence that leptin sensitivity is controlled by the circadian rhythm and that TRF periods may be most efficient when aligned with the leptin-sensitive period.-Boucsein, A., Rizwan, M. Z., Tups, A. Hypothalamic leptin sensitivity and health benefits of time-restricted feeding are dependent on the time of day in male mice.

Timing Matters: Circadian Effects on Energy Homeostasis and Alzheimer's Disease.

Metabolic syndrome and Alzheimer's disease (AD) are two major health issues in modern society causing an extraordinary financial burden for the global healthcare systems. A tight link between the pathologies of obesity and type 2 diabetes (T2D), and more recently between T2D and AD, has been discovered. Furthermore, in recent years it has become apparent that the circadian clock has an important function in controlling metabolism. This review integrates the role of the circadian clock in the development of these metabolic derangements and vice versa. Common features such as central insulin resistance, altered glycogen synthase kinase 3ß (GSK3ß) signalling, and central inflammation are discussed, and therapeutic interventions targeting those mechanisms are mentioned briefly.

Photoperiodic and Diurnal Regulation of WNT Signaling in the Arcuate Nucleus of the Female Djungarian Hamster, Phodopus sungorus.

The WNT pathway was shown to play an important role in the adult central nervous system. We previously identified the WNT pathway as a novel integration site of the adipokine leptin in mediating its neuroendocrine control of metabolism in obese mice. Here we investigated the implication of WNT signaling in seasonal body weight regulation exhibited by the Djungarian hamster (Phodopus sungorus), a seasonal mammal that exhibits profound annual changes in leptin sensitivity. We furthermore investigated whether crucial components of the WNT pathway are regulated in a diurnal manner. Gene expression of key components of the WNT pathway in the hypothalamus of hamsters acclimated to either long day (LD) or short day (SD) photoperiod was analyzed by in situ hybridization. We detected elevated expression of the genes WNT-4, Axin-2, Cyclin-D1, and SFRP-2, in the hypothalamic arcuate nucleus, a key energy balance integration site, during LD compared with SD as well as a diurnal regulation of Axin-2, Cyclin-D1, and DKK-3. Investigating the effect of photoperiod as well as leptin on the activation (phosphorylation) of the WNT coreceptor LRP-6-(Ser1490) by immunohistochemistry, we found elevated activity in the arcuate nucleus during LD relative to SD as well as after leptin treatment (2 mg/kg body weight). These findings indicate that differential WNT signaling may be associated with seasonal body weight regulation and is partially regulated in a diurnal manner in the adult brain. Furthermore, they suggest that this pathway plays a key role in the neuroendocrine regulation of body weight and integration of the leptin signal.

Central adiponectin acutely improves glucose tolerance in male mice.

Adiponectin, an adipocyte-derived hormone, regulates glucose and lipid metabolism. It is also antiinflammatory. During obesity, adiponectin levels and sensitivity are reduced. Whereas the action of adiponectin in the periphery is well established the neuroendocrine role of adiponectin is largely unknown. To address this we analyzed the expression of adiponectin and the 2 adiponectin receptors (AdipoR1 and AdipoR2) in response to fasting and to diet-induced and genetic obesity. We also investigated the acute impact of adiponectin on central regulation of glucose homeostasis. Adiponectin (1 µg) was injected intracerebroventricularly (ICV), and glucose tolerance tests were performed in dietary and genetic obese mice. Finally, the influence of ICV adiponectin administration on central signaling cascades regulating glucose homeostasis and on markers of hypothalamic inflammation was assessed. Gene expression of adiponectin was down-regulated whereas AdipoR1 was up-regulated in the arcuate nucleus of fasted mice. High-fat (HF) feeding increased AdipoR1 and AdipoR2 gene expression in this region. In mice on a HF diet and in leptin-deficient mice acute ICV adiponectin improved glucose tolerance 60 minutes after injection, whereas normoglycemia in control mice was unaffected. ICV adiponectin increased pAKT, decreased phospho-AMP-activated protein kinase, and did not change phospho-signal transducer and activator of transcription 3 immunoreactivity. In HF-fed mice, ICV adiponectin reversed parameters of hypothalamic inflammation and insulin resistance as determined by the number of phospho-glycogen synthase kinase 3 ß(Ser9) and phospho-c-Jun N-terminal kinase (Thr183/Tyr185) immunoreactive cells in the arcuate nucleus and ventromedial hypothalamus. This study demonstrates that the insulin-sensitizing properties of adiponectin are at least partially based on a neuroendocrine mechanism that involves centrally synthesized adiponectin.

Overexpression of suppressor of cytokine signaling 3 in the arcuate nucleus of juvenile Phodopus sungorus alters seasonal body weight changes.

The profound seasonal cycle in body weight exhibited by the Djungarian hamster (Phodopus sungorus) is associated with the development of hypothalamic leptin resistance during long day photoperiod (LD, 16:8 h light dark cycle), when body weight is elevated relative to short day photoperiod (SD, 8:16 h light dark cycle). We previously have shown that this seasonal change in physiology is associated with higher levels of mRNA for the potent inhibitor of leptin signaling, suppressor of cytokine signaling-3 (SOCS3), in the arcuate nucleus (ARC) of LD hamsters relative to hamsters in SD. The alteration in SOCS3 gene expression preceded the body weight change suggesting that SOCS3 might be the molecular switch of seasonal body weight changes. To functionally characterize the role of SOCS3 in seasonal body weight regulation, we injected SOCS3 expressing recombinant adeno-associated virus type-2 (rAAV2-SOCS3) constructs into the ARC of leptin sensitive SD hamsters immediately after weaning. Hamsters that received rAAV2 expressing enhanced green fluorescent protein (rAAV2-EGFP) served as controls. ARC-directed SOCS3 overexpression led to a significant increase in body weight over a period of 12 weeks without fully restoring the LD phenotype. This increase was partially due to elevated brown and white adipose tissue mass. Gene expression of pro-opiomelanocortin was increased while thyroid hormone converting enzyme DIO3 mRNA levels were reduced in SD hamsters with SOCS3 overexpression. In conclusion, our data suggest that ARC-directed SOCS3 overexpression partially overcomes the profound seasonal body weight cycle exhibited by the hamster which is associated with altered pro-opiomelanocortin and DIO3 gene expression.