Hyperinsulinemic Glucose Clamp Research Articles

Decreased branched-chain amino acids and elevated fatty acids during antecedent hypoglycemia in type 1 diabetes

IntroductionHypoglycemia is a major limiting factor in achieving recommended glycemic targets for people with type 1 diabetes. Exposure to recurrent hypoglycemia results in blunted hormonal counter-regulatory and symptomatic responses to...

Dual amylin and calcitonin receptor agonist treatment improves insulin sensitivity and increases muscle-specific glucose uptake independent of weight loss

Dual amylin and calcitonin receptor agonists (DACRAs) are known to induce significant weight loss as well as improve glucose tolerance, glucose control, and insulin action in rats. However, to what extent DACRAs affect insulin sensitivity beyond that induced by weight loss and if DACRAs affect glucose turnover including tissue-specific glucose uptake is still unknown. Hyperinsulinemic glucose clamp studies were carried out in pre-diabetic ZDSD and diabetic ZDF rats treated with either the DACRA KBP or the long-acting DACRA KBP-A for 12 days. The glucose rate of disappearance was assessed using 3-3H glucose and tissue-specific glucose uptake was evaluated using 14C-2-deoxy-D-glucose (14C-2DG). In diabetic ZDF rats, KBP treatment significantly reduced fasting blood glucose and improved insulin sensitivity independent of weight loss. Furthermore, KBP increased the rate of glucose clearance, likely by increasing glucose storage, but without altering the endogenous glucose production. This was confirmed in pre-diabetic ZDSD rats. Direct assessment of tissue-specific glucose uptake showed, that both KBP and KBP-A significantly increased glucose uptake in muscles. In summary, KBP treatment significantly improved insulin sensitivity in diabetic rats and markedly increased glucose uptake in muscles. Importantly, in addition to their well-established weight loss potential, the KBPs have an insulin-sensitizing effect independent of weight loss, highlighting DACRAs as promising agents for the treatment of type 2 diabetes and obesity.

Chronic hyperglycaemia increases the vulnerability of the hippocampus to oxidative damage induced during post-hypoglycaemic hyperglycaemia in a mouse model of chemically induced type 1 diabetes

Aims/hypothesisChronic hyperglycaemia and recurrent hypoglycaemia are independently associated with accelerated cognitive decline in type 1 diabetes. Recurrent hypoglycaemia in rodent models of chemically induced (streptozotocin [STZ]) diabetes leads to cognitive impairment in memory-related tasks associated with hippocampal oxidative damage. This study examined the hypothesis that post-hypoglycaemic hyperglycaemia in STZ-diabetes exacerbates hippocampal oxidative stress and explored potential contributory mechanisms.MethodsThe hyperinsulinaemic glucose clamp technique was used to induce equivalent hypoglycaemia and to control post-hypoglycaemic glucose levels in mice with and without STZ-diabetes and Nrf2−/− mice (lacking Nrf2 [also known as Nfe2l2]). Subsequently, quantitative proteomics based on stable isotope labelling by amino acids in cell culture and biochemical approaches were used to assess oxidative damage and explore contributory pathways.ResultsEvidence of hippocampal oxidative damage was most marked in mice with STZ-diabetes exposed to post-hypoglycaemic hyperglycaemia; these mice also showed induction of Nrf2 and the Nrf2 transcriptional targets Sod2 and Hmox-1. In this group, hypoglycaemia induced a significant upregulation of proteins involved in alternative fuel provision, reductive biosynthesis and degradation of damaged proteins, and a significant downregulation of proteins mediating the stress response. Key differences emerged between mice with and without STZ-diabetes following recovery from hypoglycaemia in proteins mediating the stress response and reductive biosynthesis.Conclusions/interpretationThere is a disruption of the cellular response to a hypoglycaemic challenge in mice with STZ-induced diabetes that is not seen in wild-type non-diabetic animals. The chronic hyperglycaemia of diabetes and post-hypoglycaemic hyperglycaemia act synergistically to induce oxidative stress and damage in the hippocampus, possibly leading to irreversible damage/modification to proteins or synapses between cells. In conclusion, recurrent hypoglycaemia in sub-optimally controlled diabetes may contribute, at least in part, to accelerated cognitive decline through amplifying oxidative damage in key brain regions, such as the hippocampus.Data availabilityThe datasets generated during and/or analysed during the current study are available in ProteomeXchange, accession no. 1-20220824-173727 (www.proteomexchange.org). Additional datasets generated during and/or analysed during the present study are available from the corresponding author upon reasonable request.Graphical abstract

SPINA Carb: a simple mathematical model supporting fast in-vivo estimation of insulin sensitivity and beta cell function

Modelling insulin-glucose homeostasis may provide novel functional insights. In particular, simple models are clinically useful if they yield diagnostic methods. Examples include the homeostasis model assessment (HOMA) and the quantitative insulin sensitivity check index (QUICKI). However, limitations of these approaches have been criticised. Moreover, recent advances in physiological and biochemical research prompt further refinement in this area. We have developed a nonlinear model based on fundamental physiological motifs, including saturation kinetics, non-competitive inhibition, and pharmacokinetics. This model explains the evolution of insulin and glucose concentrations from perturbation to steady-state. Additionally, it lays the foundation of a structure parameter inference approach (SPINA), providing novel biomarkers of carbohydrate homeostasis, namely the secretory capacity of beta-cells (SPINA-GBeta) and insulin receptor gain (SPINA-GR). These markers correlate with central parameters of glucose metabolism, including average glucose infusion rate in hyperinsulinemic glucose clamp studies, response to oral glucose tolerance testing and HbA1c. Moreover, they mirror multiple measures of body composition. Compared to normal controls, SPINA-GR is significantly reduced in subjects with diabetes and prediabetes. The new model explains important physiological phenomena of insulin-glucose homeostasis. Clinical validation suggests that it may provide an efficient biomarker panel for screening purposes and clinical research.

Hypoglycemia attenuates acute amylin-induced reduction of food intake in male rats

The ability of amylin to inhibit gastric emptying and glucagon secretion in rats is reduced under hypoglycemic conditions. These effects are considered part of a fail-safe mechanism that prevents amylin from further decreasing nutrient supply when blood glucose levels are low. Because these actions and amylin-induced satiation are mediated by the area postrema (AP), it is plausible that these phenomena are based on the co-sensitivity of AP neurons to amylin and glucose. Using hyperinsulinemic glucose clamps in unrestrained and freely-feeding rats, we investigated whether amylin's ability to inhibit food intake is also reduced by hypoglycemia (HYPO). Following an 18 h fast, rats were infused with insulin and glucose for 45 min to clamp blood glucose at baseline levels (between 90 and 100 mg/dL). HYPO (approximately 55 mg/dL) was induced between 45 and 60 min and then maintained for the remainder of the clamp. Rats were injected with amylin (20 µg/kg) or saline and offered normal chow at 85 min. Food intake was measured at 30 and 60 min after amylin. Control hyperinsulinemic/euglycemic (EU) rats were maintained at approximately 150 mg/dL (which is a physiological periprandial glucose level) before and after amylin injection. Terminal experiments tested the effect of amylin to induce the phosphorylation of ERK, a marker of amylin action in the AP, in EU and HYPO conditions. Amylin significantly reduced 30- and 60-min food intake in EU rats, but the effect at 60-min was attenuated in HYPO rats. Interestingly, glucose infusion rate had to be dramatically reduced at meal onset in saline-treated, but not in amylin-treated, EU or HYPO rats; this suggests that meal-related glucose appearance in the blood was inhibited by amylin under both EU and HYPO. Finally, amylin induced a similar pERK response in the AP in EU and HYPO rats. We conclude that amylin's action to decrease eating is blunted in hypoglycemia, and this effect seems to be downstream from amylin-induced pERK in AP neurons. These data allow us to extend the idea of a hypoglycemic brake on amylin's actions to its food intake-reducing effect, but also demonstrate that amylin can buffer meal-induced glucose appearance at EU and HYPO levels.

Improvement of skeletal muscle insulin sensitivity by 1 week of SGLT2 inhibitor use.

Background and Aims:It is currently unclear whether sodium–glucose co-transporter 2 (SGLT2) inhibitor administration can improve the insulin sensitivity as well as rapidly reduce plasma glucose concentrations in humans during the early phase of treatment initiation. This study aimed to investigate the effect of SGLT2 inhibitor on insulin sensitivity in the early phase of treatment initiation.Methods and ResultsThis single-center, open label, and single-arm prospective study recruited 20 patients (14 men) with type 2 diabetes mellitus (T2DM). We examined the patients’ metabolic parameters before and 1 week after SGLT2 inhibitor (10 mg/day of empagliflozin) administration. The glucose infusion rate (GIR) was evaluated using the euglycemic hyperinsulinemic glucose clamp technique. Changes in laboratory and anthropometric parameters before and after SGLT2 inhibitor administration were analyzed according to the change in the GIR. The BMI, body fat amount, skeletal muscle amount, systolic blood pressure, and triglyceride level significantly decreased along with the treatment, while urinary glucose level and log GIR value significantly increased. Notably, changes in the GIR after SGLT2 inhibitor administration, which indicated improvement in peripheral insulin sensitivity, were negatively correlated with T2DM duration and positively with reduction in fluctuation of daily plasma glucose profiles before and after treatment.ConclusionSGLT2 inhibitor improved insulin sensitivity in the skeletal muscle independent of anthropometric changes. Patients with short duration of T2DM and insulin resistance can be good candidates for short-term SGLT2 inhibitor administration to improve insulin sensitivity in the skeletal muscle.

155-OR: ADA Presidents’ Select Abstract: Symptom Responses to Hypoglycemia Are Related to Connectivity Change between the Thalamus and Frontal Lobes

Neuroimaging studies highlight the importance of thalamic activation in response to hypoglycemia in people with and without type 1 diabetes (T1D). This activation is characteristically attenuated in impaired awareness of hypoglycaemia (IAH), a major risk factor for severe hypoglycemia. We investigated changes in connectivity of the thalamus with other brain regions during hypoglycemia. Methods: Fourteen people without diabetes (no diabetes, ND), 15 with T1D and normal awareness of hypoglycemia (NAH) and 22 with IAH, all right-handed, age, sex and gender matched, underwent a hyperinsulinemic glucose clamp during which we acquired blood oxygen level dependent fMRI at euglycemia (90mg/dL) and at onset of hypoglycemia (48mg/dL). Connectivity was studied using the CONN toolbox in SPM12. A thalamic seed was used in a seed-to-voxel analysis with and without the increase in symptoms at hypoglycemia as an explanatory regressor variable. Results: Symptom scores in response to hypoglycemia rose earliest and to the greatest levels in NAH (11.0 to 18.3, p= 0.029). The rise in symptom scores in ND was not significant at this timepoint (9.2 to 13.8, p= 0.057), whilst IAH showed no symptom change (10.5 to 9.8, p= 0.7). In ND, hypoglycemia increased thalamic connectivity with the right frontal pole (pFDR = 0.018). This did not occur in diabetes, either in NAH or IAH. The NAH group demonstrated a positive relationship between change in symptoms with change in connectivity of the thalamus and a left frontal pole region (pFDR = 0.035), whereas an overlapping area had a negative correlation in ND (pFDR = 0.001). There was no correlation in IAH. Conclusion: During hypoglycemia, those with T1D display aberrantly enhanced thalamic connectivity with brain regions responsible for complex behavior. Disruption of this network occurs in IAH and may be the mechanism for failure of perception of the onset of hypoglycemia and reduced hypoglycemia avoidance behaviors, increasing severe hypoglycemia risk. Disclosure P. Jacob: None. M. Nwokolo: Other Relationship; Self; Sanofi. O. ODaly: None. F.O. Zelaya: None. S.A. Amiel: Advisory Panel; Self; Medtronic, Novo Nordisk A/S, Roche Pharma. Other Relationship; Self; Diabetes UK. P. Choudhary: Advisory Panel; Self; Abbott, Eli Lilly and Company, Insulet Corporation, Medtronic. Research Support; Self; European Union, JDRF. Speaker’s Bureau; Self; Dexcom, Inc., Novartis AG, Novo Nordisk A/S, Sanofi-Aventis. Funding JDRF (3-SRA-2017-484-S-B)

Characteristics influencing expected cognitive performance during hypoglycaemia in type 2 diabetes

BackgroundAcute hypoglycaemia is associated with cognitive impairment in patients with type 2 diabetes. However, there is limited understanding of the relationship between patients’ expected cognitive difficulties and their objectively-measured deficits during non-severe hypoglycaemia. ObjectiveThis report investigates demographic and clinical factors associated with the discrepancy between expected (i.e., self-evaluated) and measurable (i.e., neuropsychological) cognitive functions in patients with type 2 diabetes during acute non-severe hypoglycaemia. MethodsWe performed an analysis of factors associated with the relationship between expected and measurable cognitive performance for data collected from a cohort of patients with type 2 diabetes (N = 25). Patients attended two experimental visits during which we performed hyper-insulinaemic glucose clamping; (i) non-severe hypoglycaemic clamp (plasma glucose (PG): 3.1 ± 0.3 mmol/L) and (ii) normoglycaemic clamp (PG: 5.8 ± 0.3 mmol/L), as part of a double-blinded cross-over study. During hypoglycaemia, patients’ expected cognitive performance was assessed with a visual analogue scale after which objective cognitive functions were assessed with a neuropsychological test battery. We computed a global ‘cognitive discrepancy’ composite variable with score values on a scale between -10 and +10 using a novel statistical formula that creates a discrepancy score between subjective and objective cognition. Positive values reflect more expected than objectively-measured difficulties, while negative values reflect disproportionately more objectively-measured than expected cognitive difficulties. We used paired samples t-tests to compare degree of cognitive discrepancy between conditions of hypo- and normoglycaemia, while multiple regression analysis was performed to identify factors associated with the degree and direction of the cognitive discrepancy. The significance level for the analyses was p ≤ 0.05 (two-tailed). ResultsPatients generally underestimated their cognitive abilities (M = 1.6, SD = 3.3) during hypoglycaemia compared to normoglycaemia (M = −1.0, SD = 3.5) (p = 0.2), t(23) = 2.9, p < 0.01. Underestimation of cognitive capacity during hypoglycaemia was more pronounced for patients with younger age (β = 0.5, p = 0.02), higher verbal IQ (β = 0.5, p = 0.03), and more hypoglycaemia-related shakiness (β = 0.4, p = 0.03). LimitationsThe modest sample size limits the generalizability of the findings. ConclusionsPatients with type 2 diabetes underestimated their cognitive abilities during non-severe hypoglycaemic states, especially those with younger age, higher IQ, and more hypoglycaemia-related shakiness. These patients may thus have excessive preoccupations with their cognitive difficulties in relation to cognitively challenging daily life situations.

Impaired Awareness of Hypoglycemia Disrupts Blood Flow to Brain Regions Involved in Arousal and Decision Making in Type 1 Diabetes

Impaired awareness of hypoglycemia (IAH) affects one-quarter of adults with type 1 diabetes and significantly increases the risk of severe hypoglycemia. Differences in regional brain responses to hypoglycemia may contribute to the susceptibility of this group to problematic hypoglycemia. This study investigated brain responses to hypoglycemia in hypoglycemia aware (HA) and IAH adults with type 1 diabetes, using three-dimensional pseudo-continuous arterial spin labeling (3D pCASL) functional MRI to measure changes in regional cerebral blood flow (CBF). Fifteen HA and 19 IAH individuals underwent 3D pCASL functional MRI during a two-step hyperinsulinemic glucose clamp. Symptom, hormone, global, and regional CBF responses to hypoglycemia (47 mg/dL [2.6 mmol/L]) were measured. In response to hypoglycemia, total symptom score did not change in those with IAH (P = 0.25) but rose in HA participants (P < 0.001). Epinephrine, cortisol, and growth hormone responses to hypoglycemia were lower in the IAH group (P < 0.05). Hypoglycemia induced a rise in global CBF (HA P = 0.01, IAH P = 0.04) but was not different between groups (P = 0.99). IAH participants showed reduced regional CBF responses within the thalamus (P = 0.002), right lateral orbitofrontal cortex (OFC) (P = 0.002), and right dorsolateral prefrontal cortex (P = 0.036) and a lesser decrease of CBF in the left hippocampus (P = 0.023) compared with the HA group. Thalamic and right lateral OFC differences survived Bonferroni correction. Responses to hypoglycemia of brain regions involved in arousal, decision making, and reward are altered in IAH. Changes in these pathways may disrupt IAH individuals' ability to recognize hypoglycemia, impairing their capacity to manage hypoglycemia effectively and benefit fully from conventional therapeutic pathways to restore awareness.

Experimental non-severe hypoglycaemia substantially impairs cognitive function in type 2 diabetes: a randomised crossover trial.

Previous studies have demonstrated a relationship between cognitive impairment and hypoglycaemia (<3mmol/l). This study hypothesised that non-severe insulin-induced hypoglycaemia reduces cognitive function in individuals with type 2 diabetes. In this randomised crossover study, 25 participants with type 2 diabetes attended two experimental visits with hyperinsulinaemic glucose clamping: one hypoglycaemic clamp (plasma glucose 3.0 ± 0.2mmol/l) and one euglycaemic clamp (plasma glucose 6.0 ± 0.2mmol/l). Participants were eligible if their diabetes was treated with diet or glucose-lowering medications (except sulfonylureas or insulin), age was 35-70years, BMI was 23-35kg/m2 and HbA1c was below 75mmol/mol (9%). Cognitive function was assessed with a neurocognitive test battery measuring verbal memory, executive function, sustained attention and psychomotor speed. From the examined cognitive domains, a global cognition score was constructed estimating global cognition. A measurement for psychomotor speed was selected as the primary outcome. Participants and people assessing the outcomes were blinded to group assignment. Cognitive performance was impaired during hypoglycaemia with a mean score in the primary outcome test, Symbol Digit Modalities Test measuring psychomotor speed, of 48.7 ± 9.8 (hypoglycaemia) vs 56.6 ± 12.0 (euglycaemia); i.e. a change of -7.9 points (95% CI -10.9, -4.9; p < 0.0001). In addition, hypoglycaemia reduced global cognitive score by -0.7 (95% CI -0.9, -0.6; p < 0.0001). A stable glucose plateau was achieved during both experimental visits. For the hypoglycaemic clamp, mean plasma glucose concentration (± SD) during neurocognitive testing was 3.1 (± 0.3) mmol/l. Age, sex, fasting C-peptide, counter-regulatory hormones and the severity of hypoglycaemic symptoms did not influence cognitive function. Acute non-severe hypoglycaemia (mean plasma glucose 3.1mmol/l) has a substantial negative impact on cognitive function in individuals with type 2 diabetes. ClinicalTrials.gov NCT03014011. The study was supported in part by a research grant from the Investigator Initiated Studies Program of Merck Sharp & Dohme Corp (MSD-MA-NORD-007-01). The opinions expressed in this paper are those of the authors and do not necessarily represent those of Merck Sharp & Dohme Corp. Funding was also received from Skibsreder Per Henriksen, R. og hustrus Foundation, The Danish Alzheimer Foundation and Savværksejer Jeppe Juhl og hustrus Foundation.

368-P: Effects of Mild Hypoglycaemia on Cognitive Function in Type 2 Diabetes

Background: Previous studies have demonstrated cognitive impairment during severe hypoglycaemia. This study provides quantitative results on cognitive function during an acute mild hypoglycaemic episode in patients with type 2 diabetes. Methods: In this double-blinded randomized cross-over study, 25 patients with type 2 diabetes attended two experimental visits with hyperinsulinaemic glucose clamping; one hypoglycaemic clamp (PG 3.0 ± 0.2 mmol/l) and one euglycaemic clamp (PG 6.0 ± 0.2 mmol/l). Cognitive function was assessed during each condition with a neurocognitive test battery measuring verbal memory, executive function, sustained attention and psychomotor speed. Results: The participant’s cognitive performances were impaired during hypoglycaemia with mean score in the primary outcome test, SDMT, of 48.7 (hypoglycaemia) and 56.6 (euglycaemia); the estimated treatment difference was -7.9 (95% CI -10.9, -4.9; p=&amp;lt;0.0001). The composite score of overall speed of complex cognitive processing showed a highly significant deterioration during the hypoglycaemic condition of -0.7 (95% CI -0.9, -0.6; p=&amp;lt;0.0001) (Figure). Age, sex, fasting C-peptide and hypoglycaemic symptom severity did not influence the effect of hypoglycaemia on cognitive function. Conclusion: Acute mild hypoglycaemia (3 mmol/l [54 mg/dl]) negatively affects cognitive function in patients with type 2 diabetes. Disclosure M. Nilsson: None. N.J. Jensen: None. M. Gejl: Other Relationship; Self; Novo Nordisk A/S. I. Brandslund: None. H. Storgaard: Advisory Panel; Self; Boehringer Ingelheim Pharmaceuticals, Inc. M. Zander: None. K. Miskowiak: None. J. Rungby: None. Funding Investigator Initiated Studies Program of Merck Sharp &amp; Dohme Corp.

Hypoglycemic thalamic activation in type 1 diabetes is associated with preserved symptoms despite reduced epinephrine

Brain responses to low plasma glucose may be key to understanding the behaviors that prevent severe hypoglycemia in type 1 diabetes. This study investigated the impact of long duration, hypoglycemia aware type 1 diabetes on cerebral blood flow responses to hypoglycemia. Three-dimensional pseudo-continuous arterial spin labeling magnetic resonance imaging was performed in 15 individuals with type 1 diabetes and 15 non-diabetic controls during a two-step hyperinsulinemic glucose clamp. Symptom, hormone, global cerebral blood flow and regional cerebral blood flow responses to hypoglycemia were measured. Epinephrine release during hypoglycemia was attenuated in type 1 diabetes, but symptom score rose comparably in both groups. A rise in global cerebral blood flow did not differ between groups. Regional cerebral blood flow increased in the thalamus and fell in the hippocampus and temporal cortex in both groups. Type 1 diabetes demonstrated lesser anterior cingulate cortex activation; however, this difference did not survive correction for multiple comparisons. Thalamic cerebral blood flow change correlated with autonomic symptoms, and anterior cingulate cortex cerebral blood flow change correlated with epinephrine response across groups. The thalamus may thus be involved in symptom responses to hypoglycemia, independent of epinephrine action, while anterior cingulate cortex activation may be linked to counterregulation. Activation of these regions may have a role in hypoglycemia awareness and avoidance of problematic hypoglycemia.

IRAK-1/IRS-1 Signaling Cross Talk in Human Skeletal Muscle—Role in Insulin Resistance

Interleukin-1 receptor-associated kinase 1 (IRAK-1) is downstream from IL-1 receptors and TLRs. We identified IRS-1 (pSer24) as the first physiological substrate for IRAK-1. Decreased binding of IRS-1 (pS24) to PI 3-kinase impairs insulin action. IRAK-1 k/o mice have improved metabolic insulin action. Currently unknown is the relevance of IRAK-1/IRS-1 interactions to human pathophysiology. To investigate this topic, we examined human skeletal muscle (SkM) from NGT (n=10), IGT (n=6), and T2D (n=12) (1st cohort). Fasting protein expression of IRAK-1 and phospho-IRAK-1 (p-IRAK-1, activity proxy) and IRS-1 (pS24) did not differ significantly across groups. Insulin infusion during hyperinsulinemic glucose clamp (HGC), caused acute reductions in IRS-1 (pS24) in NGT that was diminished in IGT, and absent in T2D (p &amp;lt; 0.05, vs. NGT). p-IRAK-1 was unaltered during HGC in 1st cohort. Acute insulin-induced reduction of IRS-1 (pS24) in SkM was also found in women with PCOS (2nd cohort, n=12). Insulin sensitivity improved after pioglitazone treatment (pio, 6 mo). This was associated with reduction in IRS-1 (pS24) (both fasting and HGC (acute insulin stimulation); (vs. pio pre-treatment). In a 3rd cohort, nondiabetic (n=13) and T2D subjects (n=13), associations between IRAK-1 phosphorylation in the fasting state and measures of insulin sensitivity were noted: HOMA-IR (r=0.57, p=0.01; consistent with HGC data from PCOS pre- and post-pio, and trend in 1st cohort). In sum: 1) p-IRAK-1 in SkM (activity surrogate), predicts insulin resistance (IR) in human subjects. 2) Ability of acute insulin stimulation to reduce IRS-1 (pS24) is absent in T2D and improved after pio intervention in PCOS. 3) Changes in IRAK-1 phosphorylation of IRS-1 (S24) represents cross-talk between immune signaling and insulin signaling that may cause IR in human SkM. Our findings suggest that IRS-1 (pS24) and p-IRAK-1 are biomarkers of IR that may be molecular targets for therapy of IR in human metabolic diseases. Disclosure T.P. Ciaraldi: None. S. Mudaliar: Advisory Panel; Self; AstraZeneca. Speaker's Bureau; Self; AstraZeneca. Research Support; Self; Janssen Pharmaceuticals, Inc., Intarcia Therapeutics, Inc., National Institutes of Health. L. Li: None. R. Scalia: None. X. Sun: None. R.R. Henry: Consultant; Self; Abbott, Alere Inc., AstraZeneca. Research Support; Self; AstaReal. Advisory Panel; Self; Boehringer Ingelheim Pharmaceuticals, Inc.. Consultant; Self; Bristol-Myers Squibb Company. Advisory Panel; Self; Elcelyx Therapeutics, Inc.. Research Support; Self; Eli Lilly and Company, Hitachi, Ltd.. Advisory Panel; Self; AstraZeneca. Consultant; Self; Boehringer Ingelheim Pharmaceuticals, Inc.. Advisory Panel; Self; Intarcia Therapeutics, Inc.. Consultant; Self; Intarcia Therapeutics, Inc., Ionis Pharmaceuticals, Inc., Janssen Pharmaceuticals, Inc.. Advisory Panel; Self; Johnson &amp; Johnson Services, Inc.. Research Support; Self; Lexicon Pharmaceuticals, Inc.. Consultant; Self; Ligand Pharmaceuticals, Inc.. Advisory Panel; Self; Merck &amp; Co., Inc.. Consultant; Self; Merck &amp; Co., Inc.. Research Support; Self; Viacyte, Inc.. Consultant; Self; Sanofi-Aventis. Advisory Panel; Self; Sanofi-Aventis. M. Quon: None.

Effects of hypoglycaemia on working memory and regional cerebral blood flow in type 1 diabetes: a randomised, crossover trial

Aims/hypothesisThe aim of this randomised, crossover trial was to compare cognitive functioning and associated brain activation patterns during hypoglycaemia (plasma glucose [PG] just below 3.1 mmol/l) and euglycaemia in individuals with type 1 diabetes mellitus.MethodsIn this patient-blinded, crossover study, 26 participants with type 1 diabetes mellitus attended two randomised experimental visits: one hypoglycaemic clamp (PG 2.8 ± 0.2 mmol/l, approximate duration 55 min) and one euglycaemic clamp (PG 5.5 mmol/l ± 10%). PG levels were maintained by hyperinsulinaemic glucose clamping. Cognitive functioning was assessed during hypoglycaemia and euglycaemia conditions using a modified version of the digit symbol substitution test (mDSST) and control DSST (cDSST). Simultaneously, regional cerebral blood flow (rCBF) was measured in pre-specified brain regions by six H215O-positron emission tomographies (PET) per session.ResultsWorking memory was impaired during hypoglycaemia as indicated by a statistically significantly lower mDSST score (estimated treatment difference [ETD] −0.63 [95% CI −1.13, −0.14], p = 0.014) and a statistically significantly longer response time (ETD 2.86 s [7%] [95% CI 0.67, 5.05], p = 0.013) compared with euglycaemia. During hypoglycaemia, mDSST task performance was associated with increased activity in the frontal lobe regions, superior parietal lobe and thalamus, and decreased activity in the temporal lobe regions (p < 0.05). Working memory activation (mDSST − cDSST) statistically significantly increased blood flow in the striatum during hypoglycaemia (ETD 0.0374% [95% CI 0.0157, 0.0590], p = 0.002).Conclusions/interpretationDuring hypoglycaemia (mean PG 2.9 mmol/l), working memory performance was impaired. Altered performance was associated with significantly increased blood flow in the striatum, a part of the basal ganglia implicated in regulating motor functions, memory, language and emotion.Trial registrationNCT01789593, clinicaltrials.govFundingThis study was funded by Novo Nordisk.

Hypoglycemia-Associated EEG Changes Following Antecedent Hypoglycemia in Type 1 Diabetes Mellitus.

Recurrent hypoglycemia has been shown to blunt hypoglycemia symptom scores and counterregulatory hormonal responses during subsequent hypoglycemia. We therefore studied whether hypoglycemia-associated electroencephalogram (EEG) changes are affected by an antecedent episode of hypoglycemia. Twenty-four patients with type 1 diabetes mellitus (10 with normal hypoglycemia awareness, 14 with hypoglycemia unawareness) were studied on 2 consecutive days by hyperinsulinemic glucose clamp at hypoglycemia (2.0-2.5 mmol/L) during a 1-h period. EEG was recorded, cognitive function assessed, and hypoglycemia symptom scores and counterregulatory hormonal responses were obtained. Twenty-one patients completed the study. Hypoglycemia-associated EEG changes were identified on both days with no differences in power or frequency distribution in the theta, alpha, or the combined theta-alpha band during hypoglycemia on the 2 days. Similar degree of cognitive dysfunction was also present during hypoglycemia on both days. When comparing the aware and unaware group, there were no differences in the hypoglycemia-associated EEG changes. There were very subtle differences in cognitive function between the two groups on day 2. The symptom response was higher in the aware group on both days, while only subtle differences were seen in the counterregulatory hormonal response. Antecedent hypoglycemia does not affect hypoglycemia-associated EEG changes in patients with type 1 diabetes mellitus.

The use of modified hyperinsulinemic hypoglycaemic glucose clamp to evaluate the accuracy of blood glucose monitoring systems in T1DM patients

The use of modified hyperinsulinemic hypoglycaemic glucose clamp to evaluate the accuracy of blood glucose monitoring systems in T1DM patients

The Impact of Nocturnal Hypoglycemia on Sleep in Subjects With Type 2 Diabetes.

The aim of this trial was to investigate the impact of nocturnal hypoglycemia on sleep patterns (assessed by polysomnography) and counterregulatory hormones. In this single-blinded, crossover trial, 26 subjects with type 2 diabetes attended two experimental night visits (one normoglycemic and one hypoglycemic) in randomized order. Plasma glucose (PG) levels were controlled by hyperinsulinemic glucose clamping. On the hypoglycemic night, hypoglycemia was induced after reaching sleep stage N2 by turning off glucose infusion until the PG target of 2.7-2.8 mmol/L was reached and maintained for 15 min. Thereafter, subjects were brought back to normoglycemia for the rest of the night. On the normoglycemic night, PG was maintained at 5.0-7.0 mmol/L throughout the night. During the first 4 h of sleep (0-4 h; after reaching sleep stage N2), no difference between experimental nights was observed in the rate of electroencephalography-identified arousals or awakenings, but the rate of awakenings was 27% lower during 4-8 h and 20% lower during 0-8 h on the hypoglycemic night than on the normoglycemic night (both statistically significant). Total sleep time tended to be longer on the hypoglycemic night (observed means 366 vs. 349 min, P nonsignificant). Statistically significantly higher counterregulatory hormonal responses (adrenaline, growth hormone, and cortisol) to hypoglycemia were observed compared with normoglycemia. Nocturnal hypoglycemia in patients with type 2 diabetes caused a decrease in awakening response in the 4-8-h period following the event. These findings underscore the risks associated with nocturnal hypoglycemia because nocturnal hypoglycemia potentially affects the patient's ability to wake up and respond with an adequate intake of carbohydrates.

Infrared thermographic assessment of changes in skin temperature during hypoglycaemia in patients with type 1 diabetes.

Hypoglycaemia is associated with reduced skin temperature (Ts). We studied whether infrared thermography can detect Ts changes during hypoglycaemia in patients with type 1 diabetes and how the Ts response differs between patients with normal hypoglycaemia awareness and hypoglycaemia unawareness. Twenty-four patients with type 1 diabetes (ten aware, 14 unaware) were studied during normoglycaemia (5.0-6.0 mmol/l), hypoglycaemia (2.0-2.5 mmol/l) and during recovery from hypoglycaemia (5.0-6.0 mmol/l) using hyperinsulinaemic glucose clamping. During each 1 h phase, Ts was measured twice by infrared thermography imaging in pre-defined areas (nose, glabella and the five left fingertips), symptoms of hypoglycaemia were scored and blood was sampled. Ts decreased during hypoglycaemia on the nose and glabella. The highest decrements were recorded on the nose (aware: -2.6 °C, unaware: -1.1 °C). In aware patients, the differences in temperature were statistically significant on both nose and glabella, whereas there was only a trend in the unaware group. There was a significant difference in hypoglycaemia-induced temperature changes between the groups. Patients in the aware group had higher hypoglycaemia symptom scores and higher adrenaline (epinephrine) levels during hypoglycaemia. The hypoglycaemia-associated decrement in Ts can be assessed by infrared thermography and is larger in patients with normal hypoglycaemia awareness compared with unaware patients.

Effects of acute hypoglycemia on working memory and language processing in adults with and without type 1 diabetes.

OBJECTIVETo examine the effects of hypoglycemia on language processing in adults with and without type 1 diabetes.RESEARCH DESIGN AND METHODSForty adults were studied (20 with type 1 diabetes and 20 healthy volunteers) using a hyperinsulinemic glucose clamp to lower blood glucose to 2.5 mmol/L (45 mg/dL) (hypoglycemia) for 60 min, or to maintain blood glucose at 4.5 mmol/L (81 mg/dL) (euglycemia), on separate occasions. Language tests were applied to assess the effects of hypoglycemia on the relationship between working memory and language (reading span), grammatical decoding (self-paced reading), and grammatical encoding (subject-verb agreement).RESULTSHypoglycemia caused a significant deterioration in reading span (P < 0.001; η2 = 0.37; Cohen d = 0.65) and a fall in correct responses (P = 0.005; η2 = 0.19; Cohen d = 0.41). On the self-paced reading test, the reading time for the first sentence fragment increased during hypoglycemia (P = 0.039; η2 = 0.11; Cohen d = 0.25). For the reading of the next fragment, hypoglycemia affected the healthy volunteer group more than the adults with type 1 diabetes (P = 0.03; η2 = 0.12; Cohen d = 0.25). However, hypoglycemia did not significantly affect the number of errors in sentence comprehension or the time taken to answer questions. Hypoglycemia caused a deterioration of subject-verb agreement (correct responses: P = 0.011; η2 = 0.159; Cohen d = 0.31).CONCLUSIONSHypoglycemia caused a significant deterioration in reading span and in the accuracy of subject-verb agreement, both of which are practical aspects of language involved in its everyday use. Language processing is therefore impaired during moderate hypoglycemia.

Hypoglycemia-associated changes in the electroencephalogram in patients with type 1 diabetes and normal hypoglycemia awareness or unawareness.

Hypoglycemia is associated with increased activity in the low-frequency bands in the electroencephalogram (EEG). We investigated whether hypoglycemia awareness and unawareness are associated with different hypoglycemia-associated EEG changes in patients with type 1 diabetes. Twenty-four patients participated in the study: 10 with normal hypoglycemia awareness and 14 with hypoglycemia unawareness. The patients were studied at normoglycemia (5-6 mmol/L) and hypoglycemia (2.0-2.5 mmol/L), and during recovery (5-6 mmol/L) by hyperinsulinemic glucose clamp. During each 1-h period, EEG, cognitive function, and hypoglycemia symptom scores were recorded, and the counterregulatory hormonal response was measured. Quantitative EEG analysis showed that the absolute amplitude of the θ band and α-θ band up to doubled during hypoglycemia with no difference between the two groups. In the recovery period, the θ amplitude remained increased. Cognitive function declined equally during hypoglycemia in both groups and during recovery reaction time was still prolonged in a subset of tests. The aware group reported higher hypoglycemia symptom scores and had higher epinephrine and cortisol responses compared with the unaware group. In patients with type 1 diabetes, EEG changes and cognitive performance during hypoglycemia are not affected by awareness status during a single insulin-induced episode with hypoglycemia.