Acanthosis Nigricans: A New Manifestation of Insulin Resistance in Patients Receiving Treatment with Protease Inhibitors

Correspondence Figure 1. Acanthosis nigricans in the axilla of a patient receiving treatment with protease inhibitors. Sir—Dubé [1] and Thiébaut et al. [2] have published interesting articles describing insulin resistance in patients with HIV infection who are receiving treatment with protease inhibitors. Recently , an increasing number of papers have been published which relate treatment with protease inhibitors to the appearance of insulin resistance, diabetes, hyperlipidemia, and anomalies in the distribution of corporal fat [3]. We describe a patient with HIV infection who, after beginning treatment with protease inhib-itors, developed insulin resistance, diabetes mellitus, and acanthosis nigricans. To our knowledge, such a case has not been described in the medical literature. The patient was a 36-year-old man who had had HIV infection diagnosed 5 years before presentation. He had received treatment with ritonavir, zidovu-dine, and didanosine for 19 months; this regimen was then changed to with nel-finavir, saquinavir, stavudine and nevi-rapine, which he received for 17 months. Diabetes mellitus was diagnosed 9 months after the patient started treatment with ritonavir. At the time the patient presented to our clinic, he was asymptomatic. Findings of a physical examination were as follows: height, 187 cm; weight, 91 kg; body mass index, 26 kg/m 2 ; loss of facial and gluteal fat, increase of abdominal fat; and a velvet-aspect hyperpigmentation in the axillas and elbows (figure 1). Other physical examination findings were normal. Complementary laboratory studies were performed , for which the values were as follows: blood glucose, 229 mg/dL; total cholesterol, 145 mg/dL; high-density li-poprotein cholesterol, 29 mg/dL; trigly-cerides, 174 mg/dL; CD4 count, 361 cells/ mL; and virus load, 236,000 copies/mL. A test of pancreatic reserve with glucagon was performed; the basal C-peptide level was 5.5 ng/mL, and after stimulus, it was 12 ng/mL. At that time, the patient had a basal blood glucose level of 259 mg/dL and an insulin level of 41.10 mg/dL. The insulin sensitivity score, as determined by use of the Quantitative Insulin Sensitivity Check Index [4] was 0.25, which indicates high insulin resistance. The result of a cutaneous biopsy of the axilla was compatible with acanthosis nigricans. The patient began treatment with oral hypoglycemic drugs, which resulted in good control of blood glucose levels. Acanthosis nigricans is a cutaneous marker of insulin resistance, although, in a few cases, it has also been associated