Cross-Sectional and Longitudinal Studies of "Pre-Diabetes" in the Pima Indians

Completed

• Conditions: Weight Gain; Insulin Resistance; Overweight; Obesity; Diabetes Mellitus, Type 2

• Registration Number: NCT00340132
• Lead Sponsor: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Brief Summary

Insulin resistance and a defect in early insulin secretion are risk factors for the development of type 2 diabetes mellitus. A recent longitudinal analysis which tracked the development of diabetes demonstrated that both insulin action and early insulin secretion deteriorate as individuals progress from normal to impaired glucose tolerance and then to diabetes. These results suggest that both inherent (apparent in normal glucose tolerant subjects who progress to diabetes and likely to have a genetic basis) and acquired (evident as individuals progress from NGT to IGT to diabetes and possibly environmental in origin) defects in insulin action and secretion contribute to the pathogenesis of type 2 diabetes. To identify the genetic and environmental determinants of diabetes we are continuing to determine: (1) if there are genes that segregate with metabolic risk factors for diabetes which might therefore be genetic markers for type 2 diabetes and (2) the mechanisms mediating genetic and environmental determinants of insulin resistance and impaired insulin secretion.

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Volunteers for this study will be admitted to the clinical research ward where they will undergo several tests to determine body composition, oral and intravenous glucose tolerance and in vivo insulin action. In addition, in selected subjects, adipose and/or skeletal muscle tissue will be obtained by percutaneous biopsy for in vitro studies of gene expression and insulin action in these tissues. A transformed lymphocyte cell line will be established for each subject as a permanent source of DNA for genetic studies. Genetic markers for type 2 diabetes and insulin resistance will be sought by typing each individual at positional and functional candidate loci in the hopes of finding an association between these loci and obesity, insulin secretion, insulin resistance and/or type 2 diabetes.

Detailed Description

Insulin resistance and a defect in early insulin secretion are risk factors for the development of type 2 diabetes mellitus. A recent longitudinal analysis which tracked the development of diabetes demonstrated that both insulin action and early insulin secretion deteriorate as individuals progress from normal to impaired glucose tolerance and then to diabetes. These results suggest that both inherent (apparent in normal glucose tolerant subjects who progress to diabetes and likely to have a genetic basis) and acquired (evident as individuals progress from NGT to IGT to diabetes and possibly environmental in origin) defects in insulin action and secretion contribute to the pathogenesis of type 2 diabetes. To identify the genetic and environmental determinants of diabetes we are continuing to determine: (1) if there are genes that segregate with metabolic risk factors for diabetes which might therefore be genetic markers for type 2 diabetes and (2) the mechanisms mediating genetic and environmental determinants of insulin resistance and impaired insulin secretion.

\<TAB\>

Volunteers for this study will be admitted to the clinical research ward where they will undergo several tests to determine body composition, oral and intravenous glucose tolerance and in vivo insulin action. In addition, in selected subjects, adipose and/or skeletal muscle tissue will be obtained by percutaneous biopsy for in vitro studies of gene expression and insulin action in these tissues. A transformed lymphocyte cell line will be established for each subject as a permanent source of DNA for genetic studies. Genetic markers for type 2 diabetes and insulin resistance will be sought by typing each individual at positional and functional candidate loci in the hopes of finding an association between these loci and obesity, insulin secretion, insulin resistance and/or type 2 diabetes.

Study Timeline

• Study Start: 1983-01-01
• Study First Submitted: 2006-06-19
• Study First Submitted QC: 2006-06-19
• Study First Posted: 2006-06-21
• Status Verified: 2025-01-29
• Last Update Submitted: 2025-05-15
• Last Update Posted: 2025-05-16

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 1759

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Glucose tolerance via intravenous glucose tolerance test (IVGTT)	Baseline and after 10 minutes on day 5	Measured via IVGTT after administration of a glucose bolus (25 g as a 50% solution injected over 3 minutes)
Basal endogenous glucose production	Baseline, and after 100 minutes on day 10	Assessed using deuterium (D-6,6 2H) glucose as a tracer, infused as a 10 mL bolus followed by 0.150 mL/min for a total of 350 minutes
24-hour metabolic rate	Baseline and after 23.5 hours on day 7	Assessed from the rates of caloric expenditure and substrate utilization while in the human respiratory chamber for 24 hours
Glucose tolerance via oral glucose tolerance test (OGTT)	Baseline, and after 180 minutes on day 4	Measured via OGTT after ingestion of 75 grams of glucose over 2 minutes

Trial Locations

Locations (1)

NIDDK, Phoenix; 🇺🇸 Phoenix, Arizona, United States