Fasting Glucose and the Risk of Depressive Symptoms: Instrumental-Variable Regression in the Cardiovascular Risk in Young Finns Study Karolina Wesolowska 1 & Marko Elovainio 1,2 & Taina Hintsa 1 & Markus Jokela 1 & Laura Pulkki-Råback 3 & Niina Pitkänen 4 & Jari Lipsanen 1 & Janne Tukiainen 5 & Leo-Pekka Lyytikäinen 6,7 & Terho Lehtimäki 6,7 & Markus Juonala 8,9,10 & Olli Raitakari 4,11 & Liisa Keltikangas-Järvinen 1 Published online: 4 August 2017 # International Society of Behavioral Medicine 2017 Abstract Purpose Type 2 diabetes (T2D) has been associated with de- pressive symptoms, but the causal direction of this association and the underlying mechanisms, such as increased glucose levels, remain unclear. We used instrumental-variable regression with a genetic instrument (Mendelian randomization) to exam- ine a causal role of increased glucose concentrations in the de- velopment of depressive symptoms. Method Data were from the population-based Cardiovascular Risk in Young Finns Study (n = 1217). Depressive symptoms Electronic supplementary material The online version of this article (doi:10.1007/s12529-017-9639-2) contains supplementary material, which is available to authorized users. * Karolina Wesolowska karolina.wesolowska@helsinki.fi Marko Elovainio marko.elovainio@helsinki.fi Taina Hintsa taina.hintsa@helsinki.fi Markus Jokela markus.jokela@helsinki.fi Laura Pulkki-Råback laura.pulkki-raback@helsinki.fi Niina Pitkänen niina.pitkanen@utu.fi Jari Lipsanen jari.lipsanen@helsinki.fi Janne Tukiainen janne.tukiainen@vatt.fi Leo-Pekka Lyytikäinen leo-pekka.lyytikainen@uta.fi Terho Lehtimäki terho.lehtimaki@uta.fi Markus Juonala markus.juonala@utu.fi Olli Raitakari olli.raitakari@utu.fi Liisa Keltikangas-Järvinen liisa.keltikangas-jarvinen@helsinki.fi 1 Institute of Behavioral Sciences, University of Helsinki, P.O. Box 9, (Siltavuorenpenger 1 A), 00014 Helsinki, Finland 2 National Institute for Health and Welfare, Helsinki, Finland 3 Institute of Behavioral Sciences and Helsinki Collegium for Advanced Studies, University of Helsinki, Helsinki, Finland 4 Research Center of Applied and Preventive Cardiovascular Medicine, University of Turku, Turku, Finland 5 VATT Institute for Economic Research, Helsinki, Finland 6 School of Medicine, University of Tampere, Tampere, Finland 7 Department of Clinical Chemistry, Fimlab Laboratories, Pirkanmaa Hospital District, Tampere, Finland 8 Department of Medicine, University of Turku, Turku, Finland 9 Division of Medicine, Turku University Hospital, Turku, Finland 10 Murdoch Children’ s Research Institute, Parkville, Victoria, Australia 11 Department of Clinical Physiology and Nuclear Medicine, Turku University Hospital, Turku, Finland Int.J. Behav. Med. (2017) 24:901–907 DOI 10.1007/s12529-017-9639-2