The metabolic deterioration that antedates diabetes: personal trajectories of HbA(1c) and fasting glucose as early indicators and possible triggers for intervention.

HbA(1c) testing has become an accepted means of diagnosing diabetes as an alternative to blood glucose levels. However, population-based norms of glucose and of HbA(1c) levels do not enable the detection of diabetes at an early enough stage to thwart complications. Personal trajectories of glucose levels show steep increases a number of years prior to diabetes diagnosis. Here, we hypothesize that a comparable time-dependent deviation in an individual's HbA(1c) level may be an early manifestation of disease that should prompt lifestyle modifications. We predict that analysis of personal trajectories of glucose and of HbA(1c) will promote earlier intervention and a greater reduction in disease complications than current standards, which are based on population-based norms.

Tumors, IGF-2, and hypoglycemia: insights from the clinic, the laboratory, and the historical archive.

Tumors of mesenchymal and epithelial origin produce IGF-2, which activates pathways in the tumors. In a minority of patients, the tumors (hepatomas, fibromas, and fibrosarcomas are the most common among many) release into the circulation enough IGF-2-related peptides to mimic the fasting hypoglycemia characteristic of patients with insulin-producing islet-cell tumors. Rarely, markedly elevated IGF-2 levels produce somatic changes suggestive of acromegaly. Typically, the elevated IGF-2 levels are associated with suppressed plasma levels of insulin, IGF-1, and GH. Complicating the pathophysiology are the IGF binding proteins (IGFBPs) that can bind IGF-2 and IGF-1, modifying hormone metabolism and action. IGFBP concentrations are often altered in the presence of these tumors. At the cellular level, the 3 hormone-related ligands, IGF-2, IGF-1, and insulin, all bind to 4 (or more) types of IGF-1 receptor (IGF-1R) and insulin receptor (IR). Each receptor has its own characteristic affinity for each ligand, a tyrosine kinase, and overlapping profiles of action in the target cells. The IGF-2R, in addition to binding mannose-6-phosphate-containing proteins, provides an IGF-2 degradation pathway. Recent evidence suggests IGF-2R involvement also in signal transduction. Surgery, the treatment of choice, can produce a cure. For patients not cured by surgery, multiple therapies exist, for the tumor and for hypoglycemia. Potential future therapeutic approaches are sketched. From 1910 to 1930, hypoglycemia, insulin, insulinomas, and non-islet-cell tumors were recognized. The latter third of the century witnessed the emergence of the immunoassay for insulin; the IGFs, their binding proteins, and assays to measure them; and receptors for the insulin-related peptides as well as the intracellular pathways beyond the receptor. In closing, we replace non-islet-cell tumor hypoglycemia, an outdated and misleading label, with IGF-2-oma, self-explanatory and consistent with names of other hormone-secreting tumors.

Iatrogenic osteoporosis, bilateral HIP osteonecrosis, and secondary adrenal suppression in an HIV-infected man receiving inhaled corticosteroids and ritonavir-boosted highly active antiretroviral therapy.

OBJECTIVE: To report the first case of severe osteoporosis associated with a vertebral pathologic fracture and osteonecrosis of femoral heads in an HIV-infected man receiving inhaled corticosteroids and ritonavir-boosted antiretroviral therapy. METHODS: We describe an HIV-infected man with severe osteoporosis, bilateral hip osteonecrosis, and secondary adrenal suppression, including detailed clinical, laboratory, and radiographic data, and review the related literature. RESULTS: A 60-year-old man with a 15-year history of HIV infection and a medical history of long-standing bronchiectasis treated with inhaled corticosteroids and hypogonadism treated with testosterone was referred to the endocrinology clinic after experiencing an osteoporotic vertebral fracture. He was taking ritonavir-boosted antiretroviral therapy. Osteonecrosis of both hips was also diagnosed, which required total hip replacement therapy. Laboratory evaluation revealed adrenal insufficiency due to increased effect of exogenous inhaled steroids and no other secondary causes of osteoporosis. A bone densitometry study showed osteoporosis of both hips and the lumbar spine. He was treated with intravenous pamidronate. During treatment, he developed bilateral femoral fractures after minor trauma. CONCLUSIONS: Given the potential for increased serum levels of inhaled corticosteroids in patients taking ritonavir-boosted highly active antiretroviral therapy, attention must be paid to the risk of bone loss in HIV-infected patients taking inhaled corticosteroids. Prescribing calcium and vitamin D supplementation and considering early osteoporosis screening are reasonable measures for this patient population. Interaction between inhaled corticosteroids and ritonavir may increase risk of hypothalamus-pituitary-adrenal axis suppression.