Scientists hunt for hidden clues in adult diabetes

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: Type 1 Diabetes (T1D) * age 18-35 years * age at diagnosis 13 to 30 years * Body Mass Index (BMI) 25 to 35 kg/m2 with a stable body weight (±3 kg in the past 6 months) * diagnosis of T1D according to American Diabetes Association (ADA) criteria continuously requiring insulin for survival (if in doubt, diagnosis can be confirmed by positivity of 2 or more IAAb\* at time of diagnosis, at any time or at time of recruitment) * diabetes diagnosis performed within the previous 5 years, * requiring insulin continuously since diagnosis to prevent ketosis * Fasting C-peptide levels \< 0.3 nmol/l Type 2 Diabetes (T2D) * age 40-75 years * age at diagnosis 40 to 70 years * BMI 25 to 35 kg/m2 with a stable body weight (±3 kg in the past 6 months) * diagnosis of diabetes according to ADA criteria * Diabetes diagnosis performed within the previous 5 years * Not requiring insulin * Fasting C-peptide levels \> 0.3 nmol/l Adult Onset Autoimmune Diabetes/Latent Autoimmune Diabetes of Adults (AOnAD/LADA) * age 40-75 years * age at diagnosis 40 to 70 years * BMI 25 to 35 kg/m2 with a stable body weight (±3 kg in the past 6 months) * diagnosis of diabetes according to ADA criteria * fasting C-peptide \> 0.3 nmol/l * positive for at least one islet autoantibody (IAAb\* - at time of diagnosis, at any time or at time of recruitment) * not requiring insulin or, if on insulin, treatment started at least 6 months after diagnosis Healthy Normal Volunteers (HNV) * age 40-75 years * BMI 25 to 35 kg/m2 with a stable body weight (±3 kg in the past 6 months) * No personal history of diabetes according to ADA criteria * No history of diabetes in first degree relatives (FDRs) * Fasting C-peptide levels \> 0.3 nmol/l * IAAbs are Insulin AutoAntibodies (IAA), Thyrosine phosphatase IA-2 Antibodies (IA-2 Ab), Glutamic Acid Decarboxylase Antibodies (GAD Ab), Zinc Transporter 8 Antibodies (ZnT8 Ab), Islet Cell Antibodies (ICA). Exclusion Criteria: * For T2D participants: treatment with insulin or with thiazolidinediones (TZDs). * For T1D and AOnAD/LADA participants: treatment with TZDs. * Presence of unstable cardiovascular disease (unstable angina, myocardial infarction or coronary revascularization within 6 months, clinically significant abnormalities on EKG, presence of cardiac pacemaker, implanted cardiac defibrillator) * Evidence of acute or chronic liver disease even if asymptomatic (AST or ALT \>2.5 times the upper limit of normal) * Kidney disease (creatinine \>1.6 mg/dl or estimated GFR\<60 ml/min) * Triglycerides \>500 mg/dl, LDL \>200 mg/dl * Uncontrolled hypertension (Blood Pressure BP\>160 mmHg systolic or \>100 mmHg diastolic) * Recent important weight loss (\>3 kg in 3 months) * History of drug or alcohol abuse (\> 3 drinks per day) within the last 5 years. * History of cancer within the last 5 years (skin cancers, with the exception of melanoma, may be acceptable). * History of organ transplant. * History of bariatric surgery * Bleeding or coagulation disorders requiring chronic use of blood thinners. * Current treatment with blood thinners or antiplatelet medications that cannot be safely stopped for study procedures * History of chronic pancreatitis or pancreatic surgery * Acute or chronic infections * History of HIV, active Hepatitis B or C, or Tuberculosis. * Anemia (hemoglobin \<12 g/dl in men, \<11 g/dl in women) or other chronic hematology disorders. * Use of any medications known to influence glucose, fat and/or energy metabolism within the last 3 months (e.g., growth hormone therapy, glucocorticoids \[steroids\], etc.) other than the treatment for diabetes * Thyroid dysfunction. Participants with a Thyroid Stimulating Hormone TSH \> 10 µ IU or less than 0.4 µ IU are excluded. Participants on thyroid replacement medication or on antithyroid drugs may be enrolled providing they have been on a stable dose of medication for at least 6 weeks prior to screening and their TSH is within the range specified above. * Severe asthma or chronic obstructive pulmonary disease * Initiation or change in hormone replacement therapy within the past 3 months (including, but not limited to birth control or estrogen replacement therapy) * Cushing's disease or syndrome * Drugs that affect immune, weight or metabolic function, including but not limited to: oral corticosteroids, oral or injectable anti-obesity medications. Drugs for dyslipidemia (statins, ezetimibe, etc.) and a daily full strength or baby aspirin for atherosclerosis prevention will be allowed, provided patients have been on stable doses for at least 6 weeks prior to screening and that aspirin could be safely temporarily stopped for the study * Weight \>450 lbs. (This is Dual X-ray Absorptiometry (DEXA) table weight limit) * Gastrointestinal disorders associated with malabsorption. * Pregnant or nursing females or females less than 6 months postpartum from the scheduled date of collection. * Had major surgery within 4 weeks prior to the pre-trial (screening) visit * Participation in studies involving investigational drug(s) within 30 days prior to Screening Visit 1 * Blood donation (excluding plasma donations) of approximately 1 pint (500 mL) or more within 56 days prior to Screening Visit * Allergies to milk derived or soy derived products, lactose intolerance (due to the composition of the standard liquid meal that will be used for the test) * Allergies and reactions to lidocaine. * History of eating disorders * Psychiatric disease prohibiting adherence to study protocol * Unable to provide a reliable informed consent * Presence of any condition that, in the opinion of the investigator and clinical team, compromises participant safety or data integrity or the participant's ability to complete study visits