Depression in diabetes: Possible therapeutic success through biomarkers

People with diabetes suffer from depression more frequently than average – with sometimes considerable consequences for their quality of life and the course of the disease. Researchers from the German Diabetes Center (DDZ), the Research Institute of the Diabetes Academy Mergentheim (Forschungsinstitut an der Diabetes Akademie Mergentheim, FIDAM) and the German Center for Diabetes Research (DZD) were able to show in a large-scale analysis that biomarkers for chronic inflammation levels influence the therapeutic success of depressive symptoms – however, with considerable differences in type 1 and type 2 diabetes. The findings could help to customize the treatment of depression in people with diabetes in the future. The results were recently published in the ‘Diabetologia’ journal.

People with diabetes have about twice the risk of depression as the general population. The chronic metabolic disease is stressful and often associated with anxiety, excessive demands or negative feelings of illness. Depression can impair the independent treatment of diabetes, increase the risk of complications and have a negative impact on life expectancy. This makes early diagnosis and effective treatment of depressive symptoms – whether with medication or behavioral therapy – all the more important. However, not all people with diabetes respond equally well to treatment. 

Inflammatory Markers and the Course of Depression were Examined over a Year

Inflammatory processes could play a key role, as chronic inflammatory reactions in the body are now considered to be a common biological background mechanism for both diabetes and depression. Previous studies have shown: A change in inflammatory markers in the blood can be accompanied by an improvement or worsening of a wide range of depressive symptoms. “Identifying factors associated with therapeutic success in depression is important in order to select the right therapies for people with diabetes,” explains Prof. Christian Herder, first author of the study and Head of the Inflammation working group at the DDZ.

While previous studies often focused on individual inflammatory markers, this analysis, funded by the German Research Foundation (DFG), used a broad panel of markers in the blood and differentiated between various symptoms of depression. The analysis is based on data from 521 people with type 1 or type 2 diabetes from three different intervention studies at the FIDAM, which investigated the effect of behavioral therapy on people with type 1 and type 2 diabetes and symptoms of depression. Using a questionnaire to record depressive symptoms (Center for Epidemiologic Studies Depression Scale/CES-D) and measuring 76 inflammatory markers in the blood, the research team investigated whether there was a correlation between inflammation levels and changes in the severity of depression within a year.

Contrasting Effects Depending on the Type of Diabetes

The results show a surprising pattern: In people with type 2 diabetes and higher inflammatory markers, behavioral therapy significantly improved depressive symptoms – especially cognitive-affective complaints and anhedonia (joylessness). In people with type 1 diabetes and higher inflammation levels, behavioral therapy only achieved a smaller improvement – especially in somatic symptoms such as fatigue, sleep disorders or loss of appetite.

Why the correlations between inflammatory markers and depressive symptoms differ so significantly in type 1 and type 2 diabetes has not yet been conclusively clarified. It is possible that the different forms of immune activation play a role, i.e., autoimmune processes in type 1 diabetes and metabolic inflammation in type 2 diabetes. “Further studies are needed to better understand the underlying mechanisms and the role of psychotherapeutic and anti-inflammatory treatment approaches,” emphasizes Prof. Michael Roden, Scientific Director and Spokesman of the DDZ Board and Director of the Department of Endocrinology and Diabetology at Düsseldorf University Hospital.

Significant for the Future: Precision Medicine for Psyche and Metabolism

The findings could influence future therapy selection: “People with type 2 diabetes and high inflammation levels possibly respond particularly well to a change in depressive cognitions through cognitive behavioral therapy. People with type 1 diabetes and high inflammation levels, on the other hand, could benefit more from anti-inflammatory drug therapies,” explains Prof. Norbert Hermanns from the FIDAM. 

Original Publication:
Herder, C., Zhu, A., Schmitt, A. et al. Biomarkers of inflammation and improvement in depressive symptoms in type 1 and type 2 diabetes: differential associations with depressive symptom clusters. Diabetologia (2025). Doi:https://doi.org/10.1007/s00125-025-06472-w 

Media Contact:
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Susan Jörges
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The German Diabetes Center (DDZ) serves as the German reference center for diabetes. Its objective is to contribute to the improvement of prevention, early detection, diagnosis and treatment of diabetes mellitus. At the same time, the research center aims at improving the epidemiological data situation in Germany. The DDZ coordinates the multicenter German Diabetes Study and is a point of contact for all players in the health sector. In addition, it prepares scientific information on diabetes mellitus and makes it available to the public. The DDZ is part of the Leibniz Association (Wissenschaftsgemeinschaft Gottfried Wilhelm Leibniz, WGL) and is a partner of the German Center for Diabetes Research (DZD e.V.). www.ddz.de/en 

The German Center for Diabetes Research (DZD) is a national association that brings together experts in the field of diabetes research and combines basic research, translational research, epidemiology and clinical applications. The aim is to develop novel strategies for personalized prevention and treatment of diabetes. Members are Helmholtz Munich – German Research Center for Environmental Health, the German Diabetes Center in Düsseldorf, the German Institute of Human Nutrition in Potsdam-Rehbrücke, the Paul Langerhans Institute Dresden of Helmholtz Munich at the University Medical Center Carl Gustav Carus of the TU Dresden and the Institute for Diabetes Research and Metabolic Diseases of Helmholtz Munich at the Eberhard-Karls-University of Tuebingen together with associated partners at the Universities in Heidelberg, Cologne, Leipzig, Lübeck and Munich. www.dzd-ev.de/en