Inclusion Criteria:  Clinical diagnosis of type 1 or type 2 diabetes HbA1c <10% An understanding of and willingness to follow the protocol Signed informed consent  Exclusion Criteria:  Severe hypoglycemia resulting in seizure or loss of consciousness in the 3 months prior to enrollment Hypoglycemia unawareness Have extensive skin changes/diseases at the proposed measurement site (wrist) that could interfere with the accuracy of glucose measurements. Female subjects: pregnancy, lactation period, lack of a negative pregnancy test (except in case of menopause, sterilization or hysterectomy) Serious acute or chronic disease besides diabetes mellitus or an anamnesis which might, in the opinion of the investigator, pose a risk to the subject, e.g. seizure disorder, adrenal disorder, dialysis for renal failure, cystic fibrosis, active infection Severe diabetes related complications (i.e. severe macro angiopathy, severe micro angiopathy, severe neuro-, retino- or nephropathy) when unstable (defined by event or increasing symptoms in the last 6 months) or with insufficient therapy Any incapacity or general condition that, in the opinion of the investigator, prevents adequate compliance with the study procedures, e.g. mental or visual incapacity, tremor, language barriers, alcohol or drug misuse Not able to understand, write or read German Dependency from the sponsor or the clinical investigator