Effects of Ketone Bodies on Cognition in Type 2 Diabetes

Inclusion Criteria: * Informed and written consent * Clinically diagnosed type 2 diabetes mellitus for at least 3 months (diagnosed according to the criteria of the World Health Organization (WHO)). * Normal haemoglobin ≥ 8.0 mmol/L (male) or ≥ 6.4 mmol/L (female) * Male or female participants aged 35-70 years, both inclusive. * Treated with diet or any antidiabetic medication except insulin and SGLT2i within the last 3 weeks. * HbA1c ≤ 9.5 % by local laboratory analysis. * BMI \> 23 kg/m2 and \< 35 kg/m2 Exclusion Criteria: * Receipt of any investigational medicinal product within 3 months prior to screening. * Liver disease (alanine aminotransferase (ALAT) and/or serum aspartate aminotransferase (ASAT) \>2 times normal values) or history of hepatobiliary disorder. * Nephropathy (serum creatinine levels ≥ 126 μmol/L (male) or ≥ 111 μmol/L (female)). * Cardiac problems defined as decompensated heart failure (New York Heart Association (NYHA) class III and IV) at any time and/or angina pectoris within the last 12 months and/or acute myocardial infarction at any time. * Active or recent malignant disease. * Treatment with drugs that cannot be paused for 12 hours. * Repeated resting blood pressure at screening outside the range 90-150 mmHg for systolic or 50-100 mmHg for diastolic. This exclusion criterion also pertains to subjects taking antihypertensives. * Inability to perform cognitive tests as assessed by the investigators (e.g. visual or auditory impairment). * Known abnormalities of the central nervous system or any endocrinological (with the exception of diabetes mellitus and euthyroid goiter), haematological, neurological, psychiatric diseases or other major disorders that in the opinion of the investigator precludes compliance with the protocol, evaluation of the results or represent an unacceptable risk for the participant's safety. * Proliferative retinopathy (funduscopy performed within 12 months before the screening is acceptable) and/or severe neuropathy. * Current treatment with systemic drugs, which may interfere with glucose metabolism. * Significant history of alcoholism or drug/chemical abuse as per investigator's judgement. * Current tobacco user (smoking or nicotinic product use 3 months prior to screening). * Severe hypoglycaemic event during the past 6 months. * Known hypoglycaemia unawareness. * Participants with mental incapacity or language barriers precluding adequate understanding or co-operation or who, in the opinion of the investigator or their general practitioner, should not participate in the trial. * For females only: Pregnancy, breast-feeding status or intention of becoming pregnant during the trial. * Any chronic disorder or severe disease that in the opinion of the investigator might endanger participant's safety or compliance with the protocol.