Andreas L Birkenfeld

Universitätsklinikum Tübingen · Department of Diabetology Endocrinology and Nephrology

Background: Obesity is a major public health issue, and new pharmaceuticals for weight management are needed. Therefore, we evaluated the efficacy and safety of the glucagon-like peptide-1 (GLP-1) analogue semaglutide in comparison with liraglutide and a placebo in promoting weight loss. Methods: We did a randomised, double-blind, placebo and ac...

Background Establishing cardiovascular safety of new therapies for type 2 diabetes is important. Safety data are available for the subcutaneous form of the glucagon-like peptide-1 receptor agonist semaglutide but are needed for oral semaglutide. Methods We assessed cardiovascular outcomes of once-daily oral semaglutide in an event-driven, randomiz...

Reduced expression of the Indy (I'm Not Dead, Yet) gene in D. melanogaster and its homolog in C. elegans prolongs life span and in D. melanogaster augments mitochondrial biogenesis in a manner akin to caloric restriction. However, the cellular mechanism by which Indy does this is unknown. Here, we report on the knockout mouse model of the mammalian...

Insulin action in the human brain modulates eating behaviour, whole-body metabolism and body fat distribution1,2. In particular, brain insulin action increases whole-body insulin sensitivity, but these studies were mainly performed in lean men3,4. Here we investigate metabolic and hypothalamic effects of brain insulin action in women with a focus o...

Metformin-induced glycolysis and lactate production can lead to acidosis as a life-threatening side effect, but slight increases in blood lactate levels in a physiological range were also reported in metformin-treated patients. However, how metformin increases systemic lactate concentrations is only partly understood. Because human skeletal muscle...

Background SGLT2 inhibitors are used to reduce the risk of progression of chronic kidney disease (CKD). In patients with type 2 diabetes, they have been found to reduce extracellular volume. Given the high prevalence of extracellular volume expansion and overhydration in CKD, we investigated whether SGLT2 inhibitors might correct these disturbances...

Background: The choice of induction therapy in kidney transplantation is often non-standardized and centre-specific. Clinicians can choose between depleting and non-depleting antibodies, which differ in their immunosuppressive capacity and the concomitant risk of infection. We herein present a standardized risk-stratified algorithm for induction t...

Background Solute carrier family 13 member 5 (SLC13A5) is a Na -coupled citrate co-transporter that mediates the entry of extracellular citrate into the cytosol. SLC13A5 inhibition has been proposed as a therapeutic target for reducing progression of kidney disease via its effects on citrate metabolism. However, evidence of its efficacy in humans i...

Background Heterogeneous metabolic clusters have been identified in diabetic and prediabetic states. It is not known whether such pathophysiologic clusters impact survival in at-risk persons being evaluated for coronary heart disease. Methods The LURIC Study recruited patients referred for coronary angiography at a median age of 63 (IQR 56–70) wit...

Introduction The ability to metabolize fructose to bypass the glucose pathway in near-anaerobic conditions appears to contribute to the extreme hypoxia tolerance of the naked-mole rats. Therefore, we hypothesized that exogenous fructose could improve endurance capacity and cognitive performance in humans exposed to hypoxia. Methods In a randomized...

Previously, we found that human pancreatic preadipocytes (PPAs) and islets influence each other and that the crosstalk with the fatty liver via the hepatokine fetuin-A/palmitate induces inflammatory responses. Here, we examined whether the mRNA-expression of pancreatic extracellular matrix (ECM)-forming and -degrading components differ in PPAs from...

Introduction Atrial natriuretic peptide (ANP), a hormone secreted from the heart, controls cardiovascular and renal functions including arterial blood pressure and natriuresis. ANP also exerts metabolic effects in adipose tissue, liver and skeletal muscle, and interacts with the secretion of adipokines. We tested the hypothesis that ANP lowers conc...

ZUSAMMENFASSUNG Klinische Studien zu Diabetes mellitus sind nicht nur entscheidend für die Zulassung neuer Arzneimittel. Sie testen auch etablierte Präventionsmaßnahmen und Therapieformen und schaffen neue Erkenntnisse zu Ursachen und Mechanismen der unterschiedlichen Krankheitsverläufe des Diabetes und seiner Folgen. Aktuelle Fragestellungen dazu...

A recent data-driven classification of subjects at risk for type 2 diabetes (T2D) has identified three subtypes at high risk to develop T2D and/or complications. Among these, clusters 5 and 6 were specifically insulin resistant and both had a very high risk for nephropathy, despite the fact that cluster 6 had a delayed development of T2D. We hypoth...

The Diabetes Prevention Program Outcomes Study demonstrated that even temporary resolution of prediabetes (remission) to normal glucose regulation (NGR) prevents development of T2D and vascular complications. However, cellular mechanisms are unknown. We have previously shown in the Prediabetes Lifestyle Intervention Study, a German Center for Diabe...

Introduction Insulin resistance (IR) is associated with increased risk of T2D, CV disease and CKD. Finerenone, a nonsteroidal mineralocorticoid receptor antagonist, has shown cardiorenal benefits in people with CKD and T2D. We investigated if IR is associated with risk of cardiorenal outcomes and if IR modifies finerenone efficacy in the pooled FID...

Heterogeneity in type 2 diabetes (T2D) can be represented by a tree-like structure using reverse graph-embedded dimensionality reduction. We aimed to validate this approach and study if intensified phenotyping stratifies complications. Participants (n=927) of the German Diabetes Study (GDS) with recent-onset T2D were mapped onto a two-dimensional t...

The term prediabetes describes a fasting blood glucose level that is elevated but not yet in the diabetic range, a blood glucose level that is elevated after 120 min in a standard 75‑g oral glucose tolerance test, or both. The American Diabetes Association definition also includes glycated hemoglobin A (HbA1c). The incidence of prediabetes is rapid...

Skeletal muscle mediates the beneficial effects of exercise, thereby improving insulin sensitivity and reducing the risk for type 2 diabetes. Current human skeletal muscle models in vitro are incapable of fully recapitulating its physiological functions especially muscle contractility. By supplementation of insulin-like growth factor 1 (IGF1), a gr...

Aims/hypothesis After birth, the neonatal islets gradually acquire glucose-responsive insulin secretion, a process that is subjected to maternal imprinting. Although NEFA are major components of breastmilk and insulin secretagogues, their role for functional maturation of neonatal beta cells is still unclear. NEFA are the endogenous ligands of fatt...

Insulin action in the brain effects behavioral and metabolic processes. Specifically, insulin acts on dopamine levels in the striatum, which is part of the brain reward network. We investigated if intranasal insulin administration (INI) acts on the communication of the reward network in healthy adults, and if this is influenced by peripheral insuli...

Fragestellung Bei Neudiagnose eines Diabetes mellitus Typ 2 (T2D) ist der Beginn einer Insulintherapie abhängig von der ärztlichen Beurteilung. Dies führt zu nicht selten zu hyper-/hypoglykämer Dekompensation. Daher untersuchten wir einen möglichen Zusatznutzen der C-Peptid-Glukose-Ratio (CGR) zur Prädiktion einer Insulintherapie und des glykämisch...

Aims: Insulin action in the brain influences cognitive processes, peripheral metabolism and eating behavior. However, the influence of age and peripheral insulin sensitivity on brain insulin action remains unclear. Materials and methods: We used intranasal administration of insulin and functional MRI in a randomized, placebo-controlled within-su...

Reliability, robustness, and inter-laboratory comparability of quantitative measurements is critical for clinical lipidomics studies. Lipids' different ex vivo stability in blood bears the risk of misinterpretation of data. Clear recommendations for the process of blood sample collection are required. We studied by UHPLC-high-resolution mass spectr...

Aims: Weaimed to compare theconcentrations of GLP-1, glucagon and GIP (established regulators of glucose homeostasis) and glicentin (emerging new metabolic marker)during an OGTT in patients with normal glucose tolerance (NGT), prediabetes and diabetes at onset, and one-year before, when all had prediabetes. Methods: GLP-1, glucagon, GIP and glic...

The 8th Cardiovascular Outcome Trial (CVOT) Summit on Cardiovascular, Kidney, and Glycemic Outcomes was held virtually on November 10–12, 2022. Following the tradition of previous summits, this reference congress served as a platform for in-depth discussion and exchange on recently completed outcomes trials as well as key trials important to the ca...

Background: Bempedoic acid, an ATP citrate lyase inhibitor, reduces low-density lipoprotein (LDL) cholesterol levels and is associated with a low incidence of muscle-related adverse events; its effects on cardiovascular outcomes remain uncertain. Methods: We conducted a double-blind, randomized, placebo-controlled trial involving patients who we...

Background Exercise exerts many health benefits by directly inducing molecular alterations in physically utilized skeletal muscle. Molecular adaptations of subcutaneous adipose tissue (SCAT) might also contribute to the prevention of metabolic diseases. Aim To characterize the response of human SCAT based on changes in transcripts and mitochondria...

Adeno-associated viral (AAV) vector suspensions produced in either human derived HEK cells or in Spodoptera frugiperda (Sf9) insect cells differ in terms of residual host cell components as well as species-specific post-translational modifications displayed on the AAV capsid proteins. Here we analysed the impact of these differences on the immunoge...

Aims: Effects of glycated hemoglobin (HbA1c), HbA1c variability, diabetes duration and insulin use on cardiorenal outcomes and diabetes progression in chronic kidney disease (CKD) and type 2 diabetes (T2D) are poorly understood. This post-hoc analysis of the prespecified, pooled FIDELITY dataset investigated the efficacy and safety of finerenone b...

Non-alcoholic fatty liver disease (NAFLD) is not only a consequence of insulin resistance, but it is also an important cause of insulin resistance and major non-communicable diseases (NCDs). The close relationship of NAFLD with visceral obesity obscures the role of fatty liver from visceral adiposity as the main pathomechanism of insulin resistance...

Aims: Baseline diabetic retinopathy (DR) and risk of development of microalbuminuria, kidney function decline, and cardiovascular events (CVEs) in type 2 diabetes. Methods: Post-hoc analysis of the PRIORITY study including 1758 persons with type 2 diabetes and normoalbuminuria followed for a median of 2.5 (IQR: 2.0-3.0) years. DR diagnosis inclu...

This work proposes a method for automatic standardized assessment of bone marrow volume and spatial distribution of the proton density fat fraction (PDFF) in vertebral bodies. Intra- and interindividual variability in size and shape of vertebral bodies is a challenge for comparable interindividual evaluation and monitoring of changes in the composi...

We report on a 53-year-old female patient and a 33-year-old male patient presenting with life-threatening hypercalcemic crisis caused by self-induced vitamin-D intoxication. Both patients took high doses of vitamin D 3 supplements, cumulatively up to 2,500,000–10,000,000 I.U. over several months. Accordingly, serum 25-OH-vitamin D concentrations we...

Physical exercise is a powerful measure to prevent cardiometabolic diseases. However, the individual response to lifestyle interventions is variable and cannot, to date, be predicted. N-Lactoylphenylalanine (Lac-Phe) produced during exercise has recently been shown to mediate weight loss in obese mice. Lac-Phe could also contribute to, and potentia...

The objective of this work was to investigate whether impaired insulin secretion can be restored by lifestyle intervention in specific subphenotypes of prediabetes. One thousand forty-five participants from the Prediabetes Lifestyle Intervention Study (PLIS) were assigned to 6 recently established prediabetes clusters. Insulin secretion was assesse...

Objective: The intrauterine environment is known to affect the offspring's long-term risk for obesity and diabetes. Previous data show that maternal metabolism and gestational weight gain (GWG) are associated with fetal autonomic nervous system (ANS) function, which can be assessed with heart rate variability (HRV). We investigated whether this as...

Sepsis is defined by life-threatening organ dysfunction mediated by the host’s response to infection. This can result in septic dyslipidemia, which is involved in the neutralization of pathogen-related lipids. Knowledge of the regulatory mechanisms of septic dyslipidemia is incomplete. The cytokine betatrophin/Angiopoietin-like protein 8 (ANGPTL8)...

Background Diabetic retinopathy (DR) is a microvascular complication of diabetes highly associated to cardiovascular disease and diabetic kidney disease. However, these associations are not thoroughly investigated at an early type 2 diabetes disease stage. This study therefore evaluated the association between baseline DR status and development of...

Objective Nonalcoholic fatty liver disease (NAFLD) ranges from steatosis to nonalcoholic steatohepatitis (NASH), which often progresses to hepatocellular carcinoma (HCC) through a largely undefined mechanism. NASH and HCC depend on inflammatory signaling, whose master regulator is the NFκB transcription factor family, activated by canonical and non...

Ca ²⁺ -activated K ⁺ channels of intermediate conductance (IK) are frequently overexpressed in breast cancer (BC) cells, while IK channel depletion reduces BC cell proliferation and tumorigenesis. This raises the question, of whether and mechanistically how IK activity interferes with the metabolic activity and energy consumption rates, which are f...

Background One acute bout of exercise leads to a rapid increase in the systemic cytokine concentration. Regular exercise might alter the cytokine response, in particular in beforehand untrained and obese subjects. Methods Using a proximity extension assay, we studied the effects of acute exercise as well as endurance training on a panel of 92 cyto...

Objective: Dysregulated body fat distribution is a major determinant of various diseases. In particular, increased visceral fat mass and ectopic lipids in the liver are linked to metabolic disorders such as insulin resistance and type 2 diabetes. Furthermore, interscapular fat is considered to be a metabolically active fat compartment. Methods:...

BACKGROUND Insulin resistance of the brain can unfavorably affect long-term weight maintenance and body fat distribution. Little is known if and how brain insulin sensitivity can be restored in humans. We aimed to evaluate the effects of an exercise intervention on insulin sensitivity of the brain and how this relates to exercise-induced changes in...

Inflammatory cytokines and non-esterified fatty acids (NEFAs) are obesity-linked factors that disturb insulin secretion. The aim of this study was to investigate whether pancreatic adipose tissue (pWAT) is able to generate a NEFA/cytokine overload within the pancreatic environment and as consequence to impact on insulin secretion. Pancreatic fat is...

Introduction With pre-diabetes and diabetes increasingly recognized as heterogeneous conditions, assessment of beta-cell function is gaining clinical importance to identify disease subphenotypes. Our study aims to comprehensively validate all types of surrogate indices based on oral glucose tolerance test (OGTT) and fasting measurements in comparis...