Obese men with type IIB hyperlipidemia are insulin resistant.

By using the euglycemic clamp technique and indirect calorimetry, we determined the degree of insulin resistance in 12 obese (body mass index > 27.0 kg/m2), normotensive patients with type IIB hyperlipidemia (HLIIB) (total cholesterol > or = 6.5 mmol/L and total triglycerides > or = 2.0 mmol/L) and 17 control subjects (total cholesterol < or = 6.1 mmol/L and total triglycerides < 1.8 mmol/L) who were carefully matched for sex, age, and obesity. Fasting plasma insulin was higher in HLIIB patients than in control subjects (18.4 +/- 4.6 versus 8.9 +/- 1.2 mU/L, respectively; P = .010). The rates of whole-body glucose uptake were significantly lower in HLIIB patients than in control subjects during the last hour of the clamp (42.2 +/- 3.9 versus 54.6 +/- 2.8 mumol/kg per minute, respectively; P = .013). Glucose oxidation during the last 30 minutes of the euglycemic clamp was lower in HLIIB patients than in control subjects (14.6 +/- 0.9 versus 19.0 +/- 1.3 mumol/kg per minute, respectively; P = .017). Nonoxidative glucose disposal during the last 30 minutes of the euglycemic clamp was also lower in HLIIB patients than in control subjects, but the difference was not statistically significant (27.6 +/- 3.3 versus 35.8 +/- 2.8 mumol/kg per minute, respectively; P = .069). Lipid oxidation during the clamp was completely suppressed in control subjects (-0.24 +/- 0.44 mumol/kg per minute) but was significantly less suppressed in the HLIIB patients (0.94 +/- 0.29 mumol/kg per minute, P = .024).(ABSTRACT TRUNCATED AT 250 WORDS)