Diabetes, Obesity
Conditions
Keywords
diabetes, obesity, inflammation
Brief summary
The purpose of this study is to determine whether a lipid infusion can up-regulate toll-like receptor 4 (TLR4) signaling in human subjects
Detailed description
The investigators plan to examine the effect of a lipid infusion on TLR4 expression and insulin sensitivity. A group of 30 subjects aged 18-60 years old, lean (BMI \< 26 kg/m2) normal glucose tolerant subjects without a family history of type 2 diabetes will receive a lipid or saline infusion. The subjects will be randomly assigned to first receive either a 48 hour long lipid or saline infusion. Approximately 4-6 weeks later subjects will return to undergo another study (if, in the first study they received lipid, on the second study they will receive saline, and vice versa). A near-equal number of women and men will be included in each group.
Interventions
DRUGIntralipid 20%
30 ml/h for 48 h
DRUGSaline
30 ml/h for 48 h
Sponsors
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
The University of Texas Health Science Center at San Antonio
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 60 Years
Healthy volunteers
Yes
Inclusion criteria
1. Subjects must have the following laboratory values: Hematocrit ≥ 35%, serum creatinine ≤ 1.5 mg/dl, aspartate aminotransferase (AST) \< 2 X upper limit of normal, Alanine aminotransferase (ALT) \< 2 X upper limit of normal, alkaline phosphatase \< 2 X upper limit of normal, normal urinalysis \[no glucose, trace protein, trace ketones, lipase \< 50 IU/L, no bacteria, up to 1-3 white blood cells (WBC) and red blood cells (RBC) per hpf\], and normal platelets, prothrombin time (PT) and partial thromboplastin time (PTT). 2. Female subjects must be non-lactating. Female patients are eligible only if they have a negative pregnancy test throughout the study period (or postmenopausal). Postmenopausal women taking hormone replacement will be included if they have been on a stable dose for ≥6 months. 3. Subjects whose body weight has been stable (within 2%) for at least three months.
Exclusion criteria
1. Subjects with impaired glucose tolerance based on American Diabetes Association criteria. 2. Subjects taking drugs known to affect glucose and lipid homeostasis will be excluded. Statins will be permitted if the subject has been on a stable dose for at least three months. Subjects who have taken for more than a week non-steroidal anti inflammatory drugs (NSAIDS) within two months or systemic steroids, anabolic steroids, growth hormone or immunosuppressants within 12 months will be excluded. Subjects taking low-dose (81 mg/day or less) aspirin will be allowed. 3. Patients with a history of clinically significant heart disease (New York Heart Classification greater than grade II; more than non-specific ST-T wave changes on the EKG), peripheral vascular disease (history of claudication), or pulmonary disease (dyspnea on exertion of one flight or less; abnormal breath sounds on auscultation) will not be studied. 4. Recent systemic or pulmonary embolus, impaired renal function, poorly controlled blood pressure (systolic BP\>170, diastolic BP\>95), resting heart rate \>100, electrolyte abnormalities, neuromuscular or musculoskeletal disease. 5. Subjects who smoke. 6. Subjects who engage in a regular exercise program (zero or one exercise sessions per week are allowed). 7. Any subject who has donated blood in the previous two months. 8. Any subject with a hematocrit of less than 35. 9. Subjects who are claustrophobic. 10. Women taking oral contraceptives. 11. alcohol consumption greater than 30 grams daily. 12. baseline plasma triglyceride levels over 200 mg/dl
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Muscle Insulin Sensitivity-M Value | 48 hr after lipid/saline infusion | Forty eight hrs after lipid or saline infusion, muscle insulin sensitivity will be measured by insulin clamp. The results are compared to determine whether lipid infusion reduces muscle insulin sensitivity compared to saline infusion.. The M value is defined as the exogenous glucose infusion rate at steady state (i.e, when the exogenous glucose infusion rate is equal to the rate of whole body glucose disposal). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| TLR4 Messenger Ribonucleic Acid (mRNA) in Muscle | 48 hr following lipid/saline infusion, pre-clamp | Forty eight hrs after lipid or saline infusion, muscle TLR4 mRNA levels will be measured by RT-PCR. The results are compared to determine whether lipid infusion increases muscle TLR4 mRNA expression compared to saline infusion. Saline mean was used to normalize the data for both arms. |
| Extracellular Signal-regulated Kinase (ERK) Phosphorylation in Muscle | 48 hr following lipid or saline infusion, pre-clamp | Forty eight hrs after lipid or saline infusion, muscle ERK phosphorylation will be measured by western blot. The results are compared to determine whether lipid infusion increases muscle ERK phosphorylation compared to saline infusion. Saline mean was used to normalize the data for both arms. |
Countries
United States
Participant flow
Pre-assignment details
12 of 52 participants were randomized. Of those not randomized, 40 did not meet inclusion criteria.
Participants by arm
| Arm | Count |
|---|---|
| All Study Participants Participants who were randomized to receive either lipid or saline | 12 |
| Total | 12 |
Baseline characteristics
| Characteristic | All Study Participants |
|---|---|
| Age, Continuous | 39 years STANDARD_DEVIATION 11 |
| Region of Enrollment United States | 12 participants |
| Sex: Female, Male Female | 7 Participants |
| Sex: Female, Male Male | 5 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 12 | 0 / 12 |
| serious Total, serious adverse events | 0 / 12 | 0 / 12 |
Outcome results
Primary
Muscle Insulin Sensitivity-M Value
Forty eight hrs after lipid or saline infusion, muscle insulin sensitivity will be measured by insulin clamp. The results are compared to determine whether lipid infusion reduces muscle insulin sensitivity compared to saline infusion.. The M value is defined as the exogenous glucose infusion rate at steady state (i.e, when the exogenous glucose infusion rate is equal to the rate of whole body glucose disposal).
Time frame: 48 hr after lipid/saline infusion
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Saline | Muscle Insulin Sensitivity-M Value | 9.9 mg/kg.min | Standard Error 0.7 |
| Intralipid | Muscle Insulin Sensitivity-M Value | 8.3 mg/kg.min | Standard Error 0.7 |
Secondary
Extracellular Signal-regulated Kinase (ERK) Phosphorylation in Muscle
Forty eight hrs after lipid or saline infusion, muscle ERK phosphorylation will be measured by western blot. The results are compared to determine whether lipid infusion increases muscle ERK phosphorylation compared to saline infusion. Saline mean was used to normalize the data for both arms.
Time frame: 48 hr following lipid or saline infusion, pre-clamp
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Saline | Extracellular Signal-regulated Kinase (ERK) Phosphorylation in Muscle | 1.0 densitometry value | Standard Error 0.18 |
| Intralipid | Extracellular Signal-regulated Kinase (ERK) Phosphorylation in Muscle | 1.95 densitometry value | Standard Error 0.3 |
Secondary
TLR4 Messenger Ribonucleic Acid (mRNA) in Muscle
Forty eight hrs after lipid or saline infusion, muscle TLR4 mRNA levels will be measured by RT-PCR. The results are compared to determine whether lipid infusion increases muscle TLR4 mRNA expression compared to saline infusion. Saline mean was used to normalize the data for both arms.
Time frame: 48 hr following lipid/saline infusion, pre-clamp
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Saline | TLR4 Messenger Ribonucleic Acid (mRNA) in Muscle | 1 ng TLR4 mRNA/ng Actin mRNA | Standard Error 0.15 |
| Intralipid | TLR4 Messenger Ribonucleic Acid (mRNA) in Muscle | 1.6 ng TLR4 mRNA/ng Actin mRNA | Standard Error 0.2 |