Decreased insulin action, impaired insulin secretion and increased adiposity are important risk factors for development of type 2 diabetes. These risk factors are present even when individuals have both normal fasting and two hour glucose concentrations indicating a very early role for decreased insulin secretion in the development of type 2 diabetes. In previous work we had found several bimodally expressed genes in muscle tissue. One of these, HLA-DRB1, was associated with lower risk for diabetes and higher insulin secretion in Pima Indians. As the HLA system is involve in immune regulation, therefore presence of protective HLA haplotype indicates involvement of autoimmunity in progression to type 2 diabetes in Pima Indians. To further explore this, we performed a pilot study in individuals with and without the HLA-DRB1 locus who were also discordant for diabetes status, examining both immunoprofiling of over 9,000 potential proteins and T-cell receptor genes. Our preliminary results demonstrate 200 possible antibodies that might be markers of progression to type 2 diabetes, and differences in frequencies of T-cell receptor genes between those with and without diabetes. We are planning follow-up studies in which we will attempt to validate a selection of the antibodies and further investigate the association of these T-cell receptor gene frequencies with measurements of insulin action and insulin secretion. We are continuing to investigate additional factors which control insulin secretion and insulin action. Individuals who are undergoing bariatric surgery using the following techniques: Roux-en-Y gastric bypass (RYGBP), laporoscopic band, or gastric sleeve will undergo measures of insulin action, insulin secretion and meal tests prior to and one month following the surgery. Preliminary results indicate that in individuals without diabetes one month of after surgery those who underwent RYGBP had dramatic improvements in hepatic insulin sensitivity, and more rapid glucose and hence insulin responses during meal tests. This explains the greater improvement in glycemia seen in those with diabetes undergoing RYGBP compared with other the laporoscopic band. We are continuing to perform more detailed measurements of insulin action and secretion and are continuing longer term follow-up to determine the durability of these shorter term changes. We are also comparing individuals undergoing sleeves to RYGBP. Previous predictors of weight gain based on this study have included, higher respiratory quotient, higher insulin mediated glucose uptake, lower free T3, and relatively lower energy expenditure. As variability in energy expenditure remains a potential mediator of weight change we have continued to evaluate factors related to metabolic rate.. We had also found that the concentration of the endocannabinoid , 2-arachidonoylglycerol (2-AG), in cerebrospinal fluid is higher in American Indians, and that CSF oleoylethanolamide was associated with energy expenditure. Endocannabinoids are fatty acids derivatives. In rodent models long chain fatty acids have specific roles in regulating food intake and hepatic glucose output. We measured long chain saturated, mono-unsaturated and poly-unsaturated fatty acids in CSF and investigated their associations with metabolic measurements. We found that specific mono-unsaturated fatty acids (18:1 and 16:1 or oleic and palmitoleic acid respectively) were associated with lower respiratory quotient (a measure of the ratio of carbohydrate to lipid oxidation) and lower glucose concentrations during an oral glucose tolerance test. Furthermore, we found that very long chain fatty acid concentrations in the CSF were inversely associated with 24 hour energy expenditure. These results indicate specific roles for long chain fatty acids as central signaling molecules with important peripheral effects. We are continuing to examine the role of these specific long chain fatty acids centrally and in the periphery and their effects on insulin action, energy expenditure and food intake. Genetic factors underlie adiposity and its risk factors. Mutations in the melanocortin 4 receptor gene are associated with increased body mass index and lower 24 hour energy expenditure in humans. We investigated the lifecourse effect of the MC4R mutation and found that the accelerated weight gain occurred in childhood but not in adulthood indicating a more potent effect of this mutation in early life. Furthermore, we found that presence of MC4R mutations predicted development of diabetes in childhood independent of body weight. We are now investigating how MC4R mutations may affect downstream mediators that lead to accelerated weight gain.

Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Zip Code
Frankl, Joseph; Piaggi, Paolo; Foley, James E et al. (2017) In Vitro lipolysis is associated with whole-body lipid oxidation and weight gain in humans. Obesity (Silver Spring) 25:207-214
Piaggi, Paolo; Masindova, Ivica; Muller, Yunhua L et al. (2017) A Genome-Wide Association Study Using a Custom Genotyping Array Identifies Variants in GPR158 Associated With Reduced Energy Expenditure in American Indians. Diabetes 66:2284-2295
Heinitz, S; Piaggi, P; Vinales, K L et al. (2017) Specific skeletal muscle sphingolipid compounds in energy expenditure regulation and weight gain in Native Americans of Southwestern heritage. Int J Obes (Lond) 41:1585-1593
Chang, Douglas C; Piaggi, Paolo; Hanson, Robert L et al. (2017) Autoantibodies against PFDN2 are associated with an increased risk of type 2 diabetes: A case-control study. Diabetes Metab Res Rev :
Paddock, Ethan; Hohenadel, Maximilian G; Piaggi, Paolo et al. (2017) One-hour and two-hour postload plasma glucose concentrations are comparable predictors of type 2 diabetes mellitus in Southwestern Native Americans. Diabetologia :
Chang, Douglas C; Piaggi, Paolo; Krakoff, Jonathan (2017) A Novel Approach to Predict 24-Hour Energy Expenditure Based on Hematologic Volumes: Development and Validation of Models Comparable to Mifflin-St Jeor and Body Composition Models. J Acad Nutr Diet 117:1177-1187
Reinhardt, Martin; Dey, Soumyadeep; Tom Noguchi, Constance et al. (2016) Non-hematopoietic effects of endogenous erythropoietin on lean mass and body weight regulation. Obesity (Silver Spring) 24:1530-6
Frankl, Joseph A; Thearle, Marie S; Desmarais, Cindy et al. (2016) T-cell receptor repertoire variation may be associated with type 2 diabetes mellitus in humans. Diabetes Metab Res Rev 32:297-307
Chang, Douglas C; Piaggi, Paolo; Hanson, Robert L et al. (2015) Use of a High-Density Protein Microarray to Identify Autoantibodies in Subjects with Type 2 Diabetes Mellitus and an HLA Background Associated with Reduced Insulin Secretion. PLoS One 10:e0143551
Piaggi, Paolo; Thearle, Marie S; Bogardus, Clifton et al. (2015) Fasting hyperglycemia predicts lower rates of weight gain by increased energy expenditure and fat oxidation rate. J Clin Endocrinol Metab 100:1078-87

Showing the most recent 10 out of 35 publications