Inclusion Criteria

• Informed, written consent 
• Normal blood pressure 
• Non Diabetic 
• Ages 30-65
• BMI 25.1-40 kg/m2
• Baseline lipid data to determine the presence or absence of atherogenic dyslipidemia
  • Will attempt to enroll those with fasting TGs >150 but < 400 mg/dL and/or HDL < 45 mg/dL in men, < 50 mg/dL in women with the final decision for enrollment based on the clinical judgement of the PI
• The degree of insulin resistance will be confirmed during the screening phase by an OGTT with seven time points to measure glucose and insulin
• age and gender matched healthy lean controls with a BMI ≤ 25.0 will be enrolled
  • The controls will have normal screening lipids 
  • The controls will be normotensive and will be on no chronic medications as noted above
• The following screening labs, done either at a screening visit or documented in the medical record within the previous 3 months, will be within the normal range
  • CBC
  • AST
  • Creatinine
  • TSH
  • POC pregnancy test (day of screen and day of admission)
    • Women of reproductive capability will be enrolled but  radiation is used on the inpatient study day
  • Sexually active women who are able to become pregnant (i.e. intact uterus and menses within the past 1 year) must agree to use one of the birth control methods listed below
    • Hormonal methods such as birth control pills, patches, injections, vaginal ring, or implants
    • Barrier methods (such as a condom or diaphragm) used with a spermicide (a foam, cream, or gel that kills sperm)
    • Intrauterine device (IUD)
    • Abstinence (no sex)

Exclusion Criteria

• Individuals with diabetes or uncontrolled hypertension and those taking triglyceride-lowering agents (niacin) 
• No chronic medications, especially any known to affect glucose and/or lipid metabolism, except oral contraceptives or antihistamines 
• Must tolerate being given a stable diet 
• Will not be involved in regular vigorous exercise 
• Chronic health conditions other than allergies without asthma  
• Abnormal lab results in any of the screening labs listed above.
• Pregnancy
• Known allergy or contraindication to niacin or insulin or to local anesthetics
• Frequent use of alcohol (more than 1 ounce per day) or any use of recreational drugs
• Inability or unwillingness to give written informed consent
  • For individuals who do not read and write in English, see DSMP for consent plan for subjects with English as a second language.
• Subjects who have donated a unit of blood to a blood bank within 84 days
  • Subjects who have had a venipuncture within 84 days for other reasons than blood donation to a blood bank must not have exceeded removal of 550 mL of blood