Successful Versus Failed Adaptation to High-Fat Diet–Induced Insulin Resistance: The Role of IAPP-Induced β-Cell Endoplasmic Reticulum Stress

ObjectiveObesity is a known risk factor for type 2 diabetes. However, most obese individuals do not develop diabetes because they adapt to insulin resistance by increasing beta-cell mass and insulin secretion. Islet pathology in type 2 diabetes is characterized by beta-cell loss, islet amyloid derived from islet amyloid polypeptide (IAPP), and increased beta-cell apoptosis characterized by endoplasmic reticulum (ER) stress. We hypothesized that IAPP-induced ER stress distinguishes successful versus unsuccessful islet adaptation to insulin resistance.Research design and methodsTo address this, we fed wild-type (WT) and human IAPP transgenic (HIP) rats either 10 weeks of regular chow or a high-fat diet and prospectively examined the relations among beta-cell mass and turnover, beta-cell ER stress, insulin secretion, and insulin sensitivity.ResultsA high-fat diet led to comparable insulin resistance in WT and HIP rats. WT rats compensated with increased insulin secretion and beta-cell mass. In HIP rats, in contrast, neither beta-cell function nor mass compensated for the increased insulin demand, leading to diabetes. The failure to increase beta-cell mass in HIP rats was the result of ER stress-induced beta-cell apoptosis that increased in proportion to diet-induced insulin resistance.ConclusionsIAPP-induced ER stress distinguishes the successful versus unsuccessful islet adaptation to a high-fat diet in rats. These studies are consistent with the hypothesis that IAPP oligomers contribute to increased beta-cell apoptosis and beta-cell failure in humans with type 2 diabetes

Genetic Information, Non-Discrimination, and Privacy Protections in Genetic Counseling Practice

The passage of the Genetic Information Non Discrimination Act (GINA) was hailed as a pivotal achievement that was expected to calm the fears of both patients and research participants about the potential misuse of genetic information. However, six years later, patient and provider awareness of legal protections at both the federal and state level remains discouragingly low, thereby, limiting their potential effectiveness. The increasing demand for genetic testing will expand the number of individuals and families who could benefit from obtaining accurate information about the privacy and anti-discriminatory protections that GINA and other laws extend. In this paper we describe legal protections that are applicable to individuals seeking genetic counseling, review the literature on patient and provider fears of genetic discrimination and examine their awareness and understandings of existing laws, and summarize how genetic counselors currently discuss genetic discrimination. We then present three genetic counseling cases to illustrate issues of genetic discrimination and provide relevant information on applicable legal protections. Genetic counselors have an unprecedented opportunity, as well as the professional responsibility, to disseminate accurate knowledge about existing legal protections to their patients. They can strengthen their effectiveness in this role by achieving a greater knowledge of current protections including being able to identify specific steps that can help protect genetic information