Diabetes Mellitus, Type 2, Obesity, Pre-diabetes
Conditions
Brief summary
The rationale for the proposed research is that elucidating changes in localized diacylglycerol (DAG) and sphingolipid species that predict insulin sensitivity will reveal specific localized lipids to target in therapeutics for type 2 diabetes. To attain the overall objective, the investigators propose three specific aims: 1. Identify the influence of sarcolemmal DAG and sphingolipids on cell signaling and insulin sensitivity before and after insulin sensitizing lifestyle interventions. Strong preliminary data shape the hypothesis that sarcolemmal 1,2-disaturated DAG and C18:0 ceramide species will decrease after insulin sensitizing lifestyle interventions, leading to less Protein kinase C (PKC) and Protein phosphatase 2A (PP2A) activation, and enhanced insulin signaling. Skeletal muscle DAG and sphingolipid isomers, species, localization, and de novo synthesis will be measured before and after diet-induced weight loss or exercise training interventions in obese men and women. Insulin sensitivity will be measured using insulin clamps, and muscle lipids using Liquid Chromatography Mass Spectrometry (LC/MS). 2. Determine the impact of mitochondrial/ER (endoplasmic reticulum) DAG and sphingolipids on mitochondrial function and ER stress in vivo, before and after insulin sensitizing lifestyle interventions. The investigators hypothesize, again based on preliminary data, that mitochondrial/ER sphingolipids will decrease, yet DAG will increase after insulin sensitizing lifestyle interventions, and each will associate with increased insulin sensitivity. Changes in sphingolipids will relate to increased mitochondrial function, less ER stress, reactive oxygen species (ROS), and acyl-carnitine formation, while changes in DAG will relate to increased mitochondrial content and dynamics. 3. Identify the effect of exogenous DAG and sphingolipids on mitochondrial function in vitro, before and after insulin sensitizing lifestyle interventions. The working hypothesis is that DAG and sphingolipids will reduce mitochondrial respiration and increase ROS and acyl-carnitine content, but will be attenuated after endurance exercise training. The proposed research is innovative because it represents a substantive departure from the status quo by addressing cellular compartmentalization of bioactive lipids. The investigators contribution will be significant by identifying key species and locations of DAG and sphingolipids promoting insulin resistance, as well as mechanisms explaining accumulation that could be modified by insulin sensitizing therapeutic interventions.
Detailed description
Accumulation of bioactive lipids such as diacylglycerol (DAG) and sphingolipids are one mechanism proposed to promote muscle insulin resistance. Recent data indicate these lipids are located in membranes, but the distribution and signaling of DAG and sphingolipids in specific cellular organelles which regulate insulin sensitivity is not known. There is a critical need to address these gaps in knowledge to design appropriate interventions to prevent and treat lipid-induced insulin resistance. The overall objective of this project is to determine the impact of changes in subcellular DAG and sphingolipid species, signaling, and metabolic function before and after insulin sensitizing lifestyle interventions. The investigators central hypothesis is that DAG and sphingolipids in muscle promote insulin resistance via mechanisms that are unique to location, type of lipid, and species. The rationale for the proposed research is that elucidating changes in localized DAG and sphingolipid species that predict insulin sensitivity will reveal specific localized lipids to target in therapeutics for type 2 diabetes. To attain the overall objective, the investigators propose three specific aims: 1. Identify the influence of sarcolemmal DAG and sphingolipids on cell signaling and insulin sensitivity before and after insulin sensitizing lifestyle interventions. Strong preliminary data shape the hypothesis that sarcolemmal 1,2-disaturated DAG and C18:0 ceramide species will decrease after insulin sensitizing lifestyle interventions, leading to less Protein kinase C (PKC) and Protein phosphatase 2A (PP2A) activation, and enhanced insulin signaling. Skeletal muscle DAG and sphingolipid isomers, species, localization, and de novo synthesis will be measured before and after diet-induced weight loss or exercise training interventions in obese men and women. Insulin sensitivity will be measured using insulin clamps, and muscle lipids using Liquid Chromatography Mass Spectrometry (LC/MS). 2. Determine the impact of mitochondrial/ER (endoplasmic reticulum) DAG and sphingolipids on mitochondrial function and ER stress in vivo, before and after insulin sensitizing lifestyle interventions. The investigators hypothesize, again based on preliminary data, that mitochondrial/ER sphingolipids will decrease, yet DAG will increase after insulin sensitizing lifestyle interventions, and each will associate with increased insulin sensitivity. Changes in sphingolipids will relate to increased mitochondrial function, less ER stress, reactive oxygen species (ROS), and acyl-carnitine formation, while changes in DAG will relate to increased mitochondrial content and dynamics. 3. Identify the effect of exogenous DAG and sphingolipids on mitochondrial function in vitro, before and after insulin sensitizing lifestyle interventions. The working hypothesis is that DAG and sphingolipids will reduce mitochondrial respiration and increase ROS and acyl-carnitine content, but will be attenuated after endurance exercise training. The proposed research is innovative because it represents a substantive departure from the status quo by addressing cellular compartmentalization of bioactive lipids. The investigators contribution will be significant by identifying key species and locations of DAG and sphingolipids promoting insulin resistance, as well as mechanisms explaining accumulation that could be modified by insulin sensitizing therapeutic interventions.
Interventions
BEHAVIORALLifestyle
Lifestyle changes to lose weight or become more fit
Sponsors
University of Colorado, Denver
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
30 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
* BMI: 30-40 kg/m2 * Planned physical activity: \<2 hrs/week * Glucose tolerance: 1. Normal glucose tolerance (NGT) defined as: 1. HbA1c of \<5.7%, 2. pre-diabetes as HbA1c of 5.7-6.4%, and 3. type 2 diabetes as HbA1c of ≥6.5% 2. pre-diabetes, and 3. Type 2 diabetes * Oral contraceptive use: Yes or No as long as there is no change during the study * Thyroid status: TSH between 0.5-5.0 mU/L
Exclusion criteria
* Currently taking 1. Thiazolidinediones 2. Insulin * Pregnant * Smoker (tobacco and any form of marijuana use) * Fasting triglycerides \>400mg/dl
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Percent Change in Insulin Sensitivity Compared to Baseline Measurement. | Baseline and 12 weeks | Hyperinsulinemic/euglycemic clamp measured as glucose infusion rate in mg/kg/min. |
| Percent Change in Localized Muscle Lipids Compared to Baseline | Baseline and 12 weeks | We measured changes in sarcolemmal, mitochondrial, nuclear and cytosolic lipids measured in pmol/ug protein after compared to before the interventions |
| Percent Change in Body Weight Compared to Baseline Measurement | Baseline, 3 Months | This is the percent change in body weight for each group after the 12 week intervention. |
Countries
United States
Contacts
PRINCIPAL_INVESTIGATORBryan Bergman
University of Colorado, Denver
Participant flow
Pre-assignment details
14 participants dropped out of the study prior to randomization.
Participants by arm
| Arm | Count |
|---|---|
| Weight Loss Only Lifestyle: Lifestyle changes to lose weight or become more fit | 17 |
| Exercise Only Lifestyle: Lifestyle changes to lose weight or become more fit | 16 |
| Delayed Intervention Control Control group, no intervention. Participants were offered all benefits of the interventions after study completion. | 12 |
| Total | 45 |
Baseline characteristics
| Characteristic | Weight Loss Only | Total | Delayed Intervention Control | Exercise Only |
|---|---|---|---|---|
| Age, Continuous | 39.6 years STANDARD_DEVIATION 2.4 | 39.65 years STANDARD_DEVIATION 2.5 | 39.8 years STANDARD_DEVIATION 2.7 | 39.6 years STANDARD_DEVIATION 3.1 |
| Ethnicity (NIH/OMB) Hispanic or Latino | 1 Participants | 5 Participants | 2 Participants | 2 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 16 Participants | 40 Participants | 10 Participants | 14 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Asian | 1 Participants | 3 Participants | 1 Participants | 1 Participants |
| Race (NIH/OMB) Black or African American | 1 Participants | 5 Participants | 2 Participants | 2 Participants |
| Race (NIH/OMB) More than one race | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) White | 15 Participants | 37 Participants | 9 Participants | 13 Participants |
| Region of Enrollment United States | 17 participants | 45 participants | 12 participants | 16 participants |
| Sex: Female, Male Female | 9 Participants | 23 Participants | 6 Participants | 8 Participants |
| Sex: Female, Male Male | 8 Participants | 22 Participants | 6 Participants | 8 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk |
|---|---|---|---|
| deaths Total, all-cause mortality | 0 / 17 | 0 / 16 | 0 / 12 |
| other Total, other adverse events | 0 / 17 | 0 / 16 | 0 / 12 |
| serious Total, serious adverse events | 0 / 17 | 0 / 16 | 0 / 12 |
Outcome results
Primary
Percent Change in Body Weight Compared to Baseline Measurement
This is the percent change in body weight for each group after the 12 week intervention.
Time frame: Baseline, 3 Months
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Weight Loss Only | Percent Change in Body Weight Compared to Baseline Measurement | -10.5 Percent | Standard Error 0.9 |
| Exercise Only | Percent Change in Body Weight Compared to Baseline Measurement | -0.5 Percent | Standard Error 0.5 |
| Delayed Intervention Control | Percent Change in Body Weight Compared to Baseline Measurement | 0.5 Percent | Standard Error 0.4 |
Primary
Percent Change in Insulin Sensitivity Compared to Baseline Measurement.
Hyperinsulinemic/euglycemic clamp measured as glucose infusion rate in mg/kg/min.
Time frame: Baseline and 12 weeks
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Weight Loss Only | Percent Change in Insulin Sensitivity Compared to Baseline Measurement. | 31.8 Percent change | Standard Error 8.8 |
| Exercise Only | Percent Change in Insulin Sensitivity Compared to Baseline Measurement. | 17.4 Percent change | Standard Error 8.7 |
| Delayed Intervention Control | Percent Change in Insulin Sensitivity Compared to Baseline Measurement. | -4.8 Percent change | Standard Error 9.3 |
Primary
Percent Change in Localized Muscle Lipids Compared to Baseline
We measured changes in sarcolemmal, mitochondrial, nuclear and cytosolic lipids measured in pmol/ug protein after compared to before the interventions
Time frame: Baseline and 12 weeks
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Weight Loss Only | Percent Change in Localized Muscle Lipids Compared to Baseline | Nuclear triglyceride | -20 percentage change | Standard Error 5 |
| Weight Loss Only | Percent Change in Localized Muscle Lipids Compared to Baseline | Mitochondrial triglyceride | -25 percentage change | Standard Error 6 |
| Weight Loss Only | Percent Change in Localized Muscle Lipids Compared to Baseline | Nuclear 1,2-Diacylglycerol | 20 percentage change | Standard Error 4 |
| Exercise Only | Percent Change in Localized Muscle Lipids Compared to Baseline | Nuclear triglyceride | -25 percentage change | Standard Error 5 |
| Exercise Only | Percent Change in Localized Muscle Lipids Compared to Baseline | Mitochondrial triglyceride | -30 percentage change | Standard Error 7 |
| Exercise Only | Percent Change in Localized Muscle Lipids Compared to Baseline | Nuclear 1,2-Diacylglycerol | 25 percentage change | Standard Error 5 |
| Delayed Intervention Control | Percent Change in Localized Muscle Lipids Compared to Baseline | Mitochondrial triglyceride | 5 percentage change | Standard Error 6 |
| Delayed Intervention Control | Percent Change in Localized Muscle Lipids Compared to Baseline | Nuclear 1,2-Diacylglycerol | -5 percentage change | Standard Error 1 |
| Delayed Intervention Control | Percent Change in Localized Muscle Lipids Compared to Baseline | Nuclear triglyceride | 10 percentage change | Standard Error 3 |