Inclusion Criteria Study 1.1 Diabetic Neuropathy Screening Study :  The ability to give informed consent Male or female persons >18 years of age with a diagnosis of type 1 or type 2 DM (WHO criteria)  Exclusion Criteria Study 1.1 Diabetic Neuropathy Screening Study:  Ongoing cancer treatment or other concurrent illness that will make the participant unable to attend the study on the discretion of the investigator Pregnant or breastfeeding persons Persons who, in the judgement of the investigator, may not be able to follow protocol Persons in active laser treatment for retinopathy, will be excluded from only Valsalva test (part of CAN measurements) Persons with atrial fibrillation, atrial flutter or pacemakers will not be subjected to CAN measurements.  Inclusion Criteria Substudy 1.2 Diabetic neuropathy and foot complications  The ability to give informed consent Male or female participants >39 years of age with a diagnosis of type 1 or type 2 diabetes (WHO criteria) Peripheral neuropathy diagnosed by either: Biothesiometry above age-stratified threshold values (150 participants) and/or abolished sensation to monofilament (10g) or Sudoscan and/or DPNCheck values below age-stratified threshold values (150 participants)  Exclusion Criteria Substudy 1.2 Diabetic neuropathy and foot complications  Ongoing cancer treatment or other concurrent illness that will make the patient unable to attend the study on the discretion of the investigator Pregnant or breastfeeding participants Participants who, in the judgement of the investigator, may not be able to follow the protocol Participants in active laser treatment for retinopathy, will be excluded from only Valsalva test (part of Vagus™ measurements) Participants with atrial fibrillation, atrial flutter or pacemakers will not be subjected to CAN measurements. Participants with toe or foot amputations  Inclusion Criteria Substudy 1.3 Cardiovascular autonomy neuropathy and glucose variability  Participants with type 1 diabetes, recruited from the screening study Participants with 20-80 of age  Exclusion Criteria Substudy 1.3 Cardiovascular autonomy neuropathy and glucose variability  Pregnancy Participants who, in the judgement of the investigator, is incapable to participate Participants using insulin pumps Participants in beta-blocker treatment Participants with acute infection Participants with thyroid disease Participants with alcohol abuse Participants in active laser treatment for retinopathy, will be excluded from only Valsalva test (part of Vagus™ measurements) Participants with atrial fibrillation, atrial flutter or pacemakers will not be subjected to CAN measurements. Ongoing cancer treatment or other concurrent illness that will make the patient unable to attend the study on the discretion of the investigator. Participants treated with tricyclic antidepressants