Heat shock proteins (Hsps) or stress proteins are a highly evolutionary conserved family of polypeptides that are cytoprotective, protecting proteins, lipids, and nucleic acids from damage by reducing oxidation, preventing apoptosis, suppressing proinflammatory cytokines, repairing ion channels, and aiding in protein folding (1). Hsps have recently been found to be low in individuals with type 2 diabetes, moderately low in the nondiabetic identical twin with a diabetic co-twin, and low in individuals with type 1 diabetes (2). Furthermore, in a study comparing 5,600 genes of nondiabetic subjects with those of insulin-resistant diabetic subjects, Hsp 70 was 1 of only 17 genes that were markedly lower in individuals with diabetes (3). The data suggest that low Hsps in diabetes may be an acquired as well as an inherited genetic defect. Interestingly, a study of individuals with type 1 diabetes with neuropathy observed that α-lipoic acid administration was associated with restoration of nitric oxide (NO) production, restoration of Hsp levels, and improvement in neuropathic symptoms (4). NO synthesis increases Hsp expression, whereas blocking NO synthesis lowers Hsp expression (5). Relevantly, medications that have been associated with improved outcome in diabetes—β-adrenergic blockers (6), HMG CoA reductase inhibitors (7), ACE inhibitors (8), and thiazolidinediones (9)—have all demonstrated restoration of endothelial NO synthase, which may result in Hsp expression and cytoprotection from the metabolic stresses of diabetes. Exercise increases NO production (10) and increases Hsp expression (11), perhaps contributing to the improved outcomes associated with exercise and diabetes. Importantly, a drug designed to increase Hsp expression, bimoclomol, improves diabetic retinopathy, neuropathy, nephropathy, wound healing, cardiac ischemia, and insulin resistance in laboratory diabetic animal models (12,13). Finally, heat therapy, via hot tub immersion, improves diabetic glycemic control and symptomatic diabetic neuropathy in patients with type 2 diabetes (14).

Decreased Hsps in type 1 and type 2 diabetes may be a primary factor leading to the development of diabetes and its diverse, widespread organ damage. Therapy directed at raising Hsps may limit the development of diabetes, but may also reduce the morbidity and mortality in those with diabetes.

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Address correspondence to Philip L. Hooper, PO Box 245, Glen Haven, CO 80532. E-mail: phoopermd@msn.com.