Lipodystrophy: Syndrome of severe insulin resistance

Lipodystrophy (LD) is a relatively rare complex collection of diseases that can be congenital or acquired. It is commonly missed in the clinical setting. Thus, the spectrum of disease presentation mandates clinician expertise in the pathophysiology and management of all forms of LD, obesity, and insulin resistance.

An extensive literature search of clinical trials, systematic reviews, and narrative reviews was completed in PubMed for the years 1970 to 2013. The search terms were lipodystrophy, congenital LD, acquired LD, HIV-associated LD, severe insulin resistance, adiposity, obesity, and dyslipidemia.

Lipodystrophies are a heterogeneous group of disorders with abnormal adipose tissue distribution, utilization, and metabolism. Adipose tissue can undergo significant changes in composition (hypertrophy and atrophy) in response to a nutritional state. Paradoxically, both excess and deficient adipose tissue is associated with insulin resistance and the metabolic syndrome. Bone density scan (DEXA) for body fat composition analysis or magnetic resonance imaging are optimal modalities for the assessment of abnormal adipose tissue distribution. Ongoing clinical studies suggest thiazolidinediones, insulin like growth factor-1, leptin, and growth hormone-releasing hormone as possible treatment for LPD; however, none of them is approved to reverse fat loss or treat severe insulin resistance due to LPD.

The underlying mechanisms for LPD causing insulin resistance may be lipotoxicity and derangements in adipose tissue-derived proteins (adipocytokines). However, the lack of evidence to support this model means that clinicians are on their own as they navigate through the phenotypic presentation of lipodystrophies, obesity, insulin resistance, and the metabolic syndrome.