Mikaela Sjöstrand

Glucokinase Activators AZD6370 and AZD1656 Do Not Affect the Central Counterregulatory Response to Hypoglycemia in Healthy Males

CONTEXT Glucokinase is expressed in the hypothalamus, but effects of glucokinase activators (GKAs) on counterregulatory responses to hypoglycemia are unknown. OBJECTIVE Two separate studies assessed the counterregulatory hormone responses to hypoglycemia induced by the GKAs, AZD6370 and AZD1656, compared with insulin infusion. DESIGN AND SETTING Both studies were randomized, open, two-way crossover studies, conducted in separate clinical research centers. PARTICIPANTS Both studies involved 12 healthy adult male volunteers. INTERVENTIONS Each subject received two treatments in randomized order, separated by a washout. In the AZD6370 study, overnight-fasted subjects received either a single oral AZD6370 dose (300 mg) or insulin infusion (0.8 mU/kg · min). In the AZD1656 study, overnight-fasted subjects received either a single oral dose of AZD1656 (80 mg) plus supporting insulin (1 mU/kg · min) or insulin alone (1 mU/kg · min). Insulin was added to support AZD1656 because AZD1656 alone did not produce the desired hypoglycemia. Plasma glucose was lowered during a stepwise hypoglycemic clamp with a glycemic nadir of 2.7 mmol/liter for 30 min. MAIN OUTCOME MEASURES Epinephrine, norepinephrine, GH, cortisol, and glucagon plasma levels were assessed. RESULTS No safety issues were raised. AZD6370 and AZD1656 had no effect on counterregulatory responses for norepinephrine, GH, or cortisol, but epinephrine increased slightly with AZD1656. Glucagon responses were reduced by approximately 30% with both GKAs vs. insulin. CONCLUSIONS These data suggest the central nervous system-mediated counterregulatory response during GKA-induced hypoglycemia was preserved, whereas the glucagon response was attenuated; the latter was possibly mediated by a local pancreatic effect (intraislet hyperinsulinemia) rather than by impairment of the central nervous system-mediated response.

Effects of Intrabrachial Metacholine Infusion on Muscle Capillary Recruitment and Forearm Glucose Uptake during Physiological Hyperinsulinemia in Obese, Insulin-Resistant Individuals

CONTEXT Impairment of insulin-mediated capillary recruitment in skeletal muscle contributes to a hampered glucose uptake in obesity. OBJECTIVE The objective of this study was to evaluate whether metacholine (MCh), a nitric oxide vasodilator, potentiates muscle capillary recruitment and forearm glucose uptake (FGU) during physiological hyperinsulinemia. DESIGN The double-forearm technique [i.e. infused vs. control (Ctrl) forearm] was combined with im microdialysis during an oral glucose tolerance test in 15 nondiabetic, obese subjects divided into a group of insulin-resistant (IR) (n = 7) and insulin-sensitive (n = 8) individuals. RESULTS After the oral glucose tolerance test, forearm blood flow in the Ctrl forearm was unchanged, whereas it increased about 3-fold (P < 0.0001 vs. baseline) in response to MCh. Capillary permeability surface area product for glucose (PS(glu)) (capillary recruitment), FGU, and interstitial insulin concentrations increased significantly over time (P < 0.001) in both forearms. Compared with insulin-sensitive, the IR subjects exhibited lower PS(glu) (P < 0.001) and FGU (P < 0.01) in the Ctrl arm, whereas this difference was insignificant in the MCh arm despite the blunted forearm blood flow increase. Moreover, in IR individuals MCh significantly (P < 0.05) ameliorated the delayed onset of insulin action, i.e. the FGU response to hyperinsulinemia. Finally, we found PS(glu) to be a strong and independent predictor of FGU response (adjusted R(2) 0.72; P < 0.0001). CONCLUSIONS MCh-induced vasodilation may improve the microvascular and metabolic responses to physiological hyperinsulinemia in obese, IR individuals. Further studies are required to unravel whether stimulation of nitric oxide production in skeletal muscle may represent an attractive therapeutic approach to bypassing cellular resistance to glucose disposal.

Saxagliptin improves glycemic control by modulating postprandial glucagon and C-peptide levels in Chinese patients with type 2 diabetes.

AIMS Saxagliptin reduced glycated hemoglobin (HbA1c), fasting plasma glucose (FPG), and postprandial glucose (PPG) in Asian patients with type 2 diabetes mellitus (T2DM). To understand the physiology of this effect, indices of α- and β-cell function were measured in a subpopulation of Chinese patients following a noodle mixed-meal tolerance test. METHODS Data from Chinese patients were pooled from two phase 3, 24-week studies of saxagliptin 5mg/d as monotherapy in drug-naive patients and as add-on to metformin in patients inadequately controlled with metformin alone. The end points for β- and α-cell function were change from baseline in C-peptide, insulin, and glucagon areas under the curve from 0 to 180 min (AUC0-180), insulinogenic index, and insulin sensitivity from Matsuda index after a mixed meal. Also glycemic variables, HbA1c, FPG, and PPG (AUC0-180), and homeostasis model assessment (HOMA) 2β were measured. RESULTS At 24 weeks, greater improvements in adjusted mean change from baseline HbA1c (difference vs placebo [95% CI], -0.33% [-0.50%, -0.17%], [-4 (-5.5, -1.9) mmol/mol], P<0.0001), FPG (-0.41 [-0.78, -0.03] mmol/L, P=0.03), PPG AUC0-180 (-168 [-245, -91.8] mmol min/L, P<0.0001), C-peptide AUC0-180 (19.7 [5.2, 34.2] nmol min/L, P=0.008), insulinogenic index (0.06% [0.02%, 0.09%], P=0.002), and greater suppression of glucagon secretion (glucagon AUC0-180, -322 [-493.6, -150.7] pmol min/L, P=0.0003) were observed with saxagliptin versus placebo. CONCLUSION In Chinese patients with T2DM, saxagliptin as monotherapy or as add-on to metformin improved glycemic control by modulating α- and β-cell function.

Predisposing Factors for Any and Major Hypoglycemia With Saxagliptin Versus Placebo and Overall: Analysis From the SAVOR-TIMI 53 Trial

OBJECTIVE To analyze the impact of adding saxagliptin versus placebo on the risk for hypoglycemia and to identify predictors of any and major hypoglycemia in patients with type 2 diabetes included in the Saxagliptin Assessment of Vascular Outcomes Recorded in Patients with Diabetes Mellitus–Thrombolysis in Myocardial Infarction 53 (SAVOR-TIMI 53) study. RESEARCH DESIGN AND METHODS Patients with type 2 diabetes (n = 16,492) were randomized to saxagliptin or placebo and followed for a median of 2.1 years. Associations between any hypoglycemia (symptomatic or glucose measurement <54 mg/dL) or major hypoglycemia (requiring extended assistance) and patient characteristics overall and by treatment allocation were studied. RESULTS At least one hypoglycemic event was reported in 16.6% of patients, and 1.9% reported at least one major event. Patients allocated to saxagliptin versus placebo experienced higher rates of any (hazard ratio [HR] 1.16 [95% CI 1.08, 1.25]; P < 0.001) or major (HR 1.26 [1.01, 1.58]; P = 0.038) hypoglycemia. Hypoglycemia rates (any or major) were increased with saxagliptin in patients taking sulfonylureas (SURs) but not in those taking insulin. Rates were increased with saxagliptin in those with baseline HbA1c ≤7.0% and not in those with baseline HbA1c >7.0%. Multivariate analysis of the overall population revealed that independent predictors of any hypoglycemia were as follows: allocation to saxagliptin, long duration of diabetes, increased updated HbA1c, macroalbuminuria, moderate renal failure, SUR use, and insulin use. Predictors of major hypoglycemia were allocation to saxagliptin, advanced age, black race, reduced BMI, long duration of diabetes, declining renal function, microalbuminuria, and use of short-acting insulin. Among SURs, glibenclamide was associated with increased risk of major but not any hypoglycemia. CONCLUSIONS The identification of patients at risk for hypoglycemia can guide physicians to better tailor antidiabetic therapy.

Repeated measurements of 11β-HSD-1 activity in subcutaneous adipose tissue from lean, abdominally obese, and type 2 diabetes subjects : no change following a mixed meal

The aim of this study was to measure 11β-HSD-1 activity in subcutaneous adipose tissue by an ex vivo method in three subgroups; lean, obese, and type 2 diabetes subjects, both in the fasting state and after a mixed meal and to determine the variability and reproducibility of this method. Eighteen subjects were investigated; 6 lean, 6 abdominally obese, and 6 type 2 diabetes subjects (BMI 22 ± 1, 30 ± 3 and 31 ± 3 kg/m², respectively). Needle biopsies were taken repeatedly and an index of 11β-HSD-1 activity was measured as percent conversion of (3)H-cortisone to (3)H-cortisol/100 mg tissue. For two separate biopsies taken in the fasting state on the same day, the within subjects CV was 16% and the between CV was 36% for 11β-HSD-1 activity for all subjects. For two biopsies taken in the fasting state at two different days, the total within subjects CV was 38% and the between subjects CV was 46%. Lean subjects had lower 11β-HSD-1 activity (4.8 ± 1.5% conversion of ³H-cortisone to ³H-cortisol/100 mg tissue) than both obese (14.4 ± 1.6% conversion, p<0.01) and type 2 diabetes subjects (11.7 ± 1.9% conversion, p<0.05) in the fasting state. There was no effect of a meal on 11β-HSD-1 activity in any of the three groups. The conclusions from this study are: 1) the variation coefficient for the ex vivo adipose tissue 11β-HSD-1 activity method was ∼25% for repeat measures within subjects; 2) food intake had no major impact on enzyme activity; and 3) 11β-HSD-1 activity in subcutaneous adipose tissue was significantly increased in obese subjects with or without T2DM compared to lean subjects without diabetes.

Pharmacodynamic effects of the oral glucokinase activator AZD6370 after single doses in healthy volunteers assessed with euglycaemic clamp

This study evaluated the safety, tolerability, pharmacokinetics and pharmacodynamic effects of the glucokinase activator (GKA) AZD6370 in non‐diabetic subjects, using the euglycaemic clamp to avoid the risk of hypoglycaemia.

The Selective Phosphodiesterase-5 Inhibitor Tadalafil Induces Microvascular and Metabolic Effects in Type 2 Diabetic Postmenopausal Females

OBJECTIVE The objective of the study was to explore the acute in vivo effects of the selective phosphodiesterase-5 inhibitor tadalafil on local microcirculation and regional metabolism in skeletal muscle and adipose tissue (AT). DESIGN, SETTING, AND PARTICIPANTS We studied eight postmenopausal female patients with type 2 diabetes (T2D) and eight nondiabetic controls (Ctrl) in the postabsorptive state and 180 min after the administration of tadalafil 10 mg. Intramuscular and sc microdialysis were combined with measurements of forearm (FBF) and AT blood flow as well as with arterial and deep venous blood sampling. Muscle capillary recruitment, as ascertained by the permeability surface area product for glucose (PS(glu)), forearm glucose uptake (FGU), interstitial lactate, and glycerol concentrations, was measured. RESULTS When compared with Ctrl, T2D patients exhibited lower (P = 0.01) PS(glu) but similar FGU and FBF. After tadalafil, PS(glu) (P = 0.01) and muscle interstitial-arterial (I-A) lactate concentration gradient (P < 0.01) increased significantly in both groups, whereas FBF, FGU, and I-A glycerol remained unchanged. In AT, tadalafil did not significantly affect local blood flow, whereas the sc interstitial (I) lactate and I-A lactate concentrations increased (P < 0.01), and the I-A glycerol decreased in both groups. Finally, in multivariate analysis the PS(glu) was a strong and independent predictor of muscle glucose disposal (β: 0.737 and 0.963, P < 0.05, in Ctrl and T2D, respectively). CONCLUSIONS Tadalafil emerges as an acutely acting modulator of microvascular recruitment and glucose metabolism in skeletal muscle and adipose tissue. We suggest that selective phosphodiesterase-5 blockade may provide a path forward to new therapeutics in the setting of insulin resistance.

Cardiovascular Outcomes According to Urinary Albumin and Kidney Disease in Patients With Type 2 Diabetes at High Cardiovascular Risk: Observations From the SAVOR-TIMI 53 Trial

Importance An elevated level of urinary albumin to creatinine ratio (UACR) is a marker of renal dysfunction and predictor of kidney failure/death in patients with type 2 diabetes. The prognostic use of UACR in established cardiac biomarkers is not well described. Objective To evaluate whether UACR offers incremental prognostic benefit beyond risk factors and established plasma cardiovascular biomarkers. Design, Setting, and Participants The Saxagliptin Assessment of Vascular Outcomes Recorded in Patients With Diabetes Mellitus–Thrombolysis in Myocardial Infarction (SAVOR-TIMI) 53 study was performed from May 2010 to May 2013 and evaluated the safety of saxagliptin vs placebo in patients with type 2 diabetes with overt cardiovascular disease or multiple risk factors. Median follow-up was 2.1 years (interquartile range, 1.8-2.3 years). Interventions Patients were randomized to saxagliptin vs placebo plus standard care. Main Outcomes and Measures Baseline UACR was measured in 15 760 patients (95.6% of the trial population) and categorized into thresholds. Results Of 15 760 patients, 5205 were female (33.0%). The distribution of UARC categories were: 5805 patients (36.8%) less than 10 mg/g, 3891 patients (24.7%) at 10 to 30 mg/g, 4426 patients (28.1%) at 30 to 300 mg/g, and 1638 patients (10.4%) at more than 300 mg/g. When evaluated without cardiac biomarkers, there was a stepwise increase with each higher UACR category in the incidence of the primary composite end point (cardiovascular death, myocardial infarction, or ischemic stroke) (3.9%, 6.9%, 9.2%, and 14.3%); cardiovascular death (1.4%, 2.6%, 4.1%, and 6.9%); and hospitalization for heart failure (1.5%, 2.5%, 4.0%, and 8.3%) (adjusted P < .001 for trend). The net reclassification improvement at the event rate for each end point was 0.081 (95% CI, 0.025 to 0.161), 0.129 (95% CI, 0.029 to 0.202), and 0.056 (95% CI, −0.005 to 0.141), respectively. The stepwise increased cardiovascular risk associated with a UACR of more than 10 mg/g was also present within each chronic kidney disease category. The UACR was associated with outcomes after including cardiac biomarkers. However, the improvement in discrimination and reclassification was attenuated; net reclassification improvement at the event rate was 0.022 (95% CI, −0.022 to 0.067), −0.008 (−0.034 to 0.053), and 0.043 (−0.030 to 0.052) for the primary end point, cardiovascular death, and hospitalization for heart failure, respectively. Conclusions and Relevance In patients with type 2 diabetes, UACR was independently associated with increased risk for a spectrum of adverse cardiovascular outcomes. However, the incremental cardiovascular prognostic value of UACR was minimal when evaluated together with contemporary cardiac biomarkers. Trial Registration clinicaltrials.gov Identifier: NCT01107886

Continuous inhibition of 11β‐hydroxysteroid dehydrogenase type I in adipose tissue leads to tachyphylaxis in humans and rats but not in mice

11β‐hydroxysteroid dehydrogenase type I (11β‐HSD1), a target for Type 2 diabetes mellitus, converts inactive glucocorticoids into bioactive forms, increasing tissue concentrations. We have compared the pharmacokinetic‐pharmacodynamic (PK/PD) relationship of target inhibition after acute and repeat administration of inhibitors of 11β‐HSD1 activity in human, rat and mouse adipose tissue (AT).

Atropine improves insulin sensitivity in both lean and abdominally obese subjects.

BACKGROUND Dysregulated autonomic nerve activity may contribute to the development of type 2 diabetes. The aim of this study was to assess the effects of an anticholinergic agent, atropine, and a cholinergic agent, physostigmine, on insulin sensitivity in lean and abdominally obese subjects. SUBJECTS AND METHODS In a single-blinded three-way crossover study, six lean and six abdominally obese nondiabetic subjects [three males and three females in each group; age, 43.8 ± 14.8 vs. 46.8 ± 4.8 yr (mean ± sd); body mass index, 22.6 ± 1.7 vs. 28.8 ± 1.3 kg/m(2); and waist circumference, 85 ± 2 vs. 99 ± 6 cm, respectively] were given iv infusions with atropine (15 μg/kg bolus, 4 μg/kg · h infusion), physostigmine (0.12 μg/kg · min) or saline (0.9% NaCl) in a randomized treatment order. Infusions were started 30 min before and continued throughout a 120-min euglycemic (5.6 mm) hyperinsulinemic (40 mU/m(2) · min) clamp. RESULTS Insulin sensitivity (M-value, i.e. glucose infusion rate divided by lean body mass) during the last 60 min of the clamp was higher during infusion with atropine than saline (9.2 ± 1.0 vs. 7.6 ± 1.0 mg/kg lean body mass · min, mean ± sem; P = 0.015) in all subjects. Physostigmine did not differ significantly from saline (8.2 ± 1.0). M-values were significantly higher in lean vs. obese [atropine, 11.6 ± 1.4 vs. 7.6 ± 1.3; physostigmine, 10.8 ± 1.3 vs. 6.3 ± 1.3; and saline, 9.1 ± 1.4 vs. 6.4 ± 1.3, respectively (all P < 0.05)], but the incremental effect of atropine vs. saline did not differ consistently between groups. CONCLUSION Insulin sensitivity was higher during a short-term atropine infusion compared with saline in both lean and abdominally obese subjects. This insulin-sensitizing effect of cholinergic blockade is unexpected, and the underlying mechanisms should be further investigated.