CARBOHYDRATE-METABOLISM IN INSULIN-RESISTANCE - GLUCOSE-UPTAKE AND LACTATE PRODUCTION BY ADIPOSE AND FOREARM TISSUES IN-VIVO BEFORE AND AFTER A MIXED MEAL

1. To examine whether insulin resistance in vivo is manifest equally i n both muscle and adipose tissues, we measured arteriovenous glucose a nd lactate fluxes across forearm (muscle) and abdominal subcutaneous ( adipose) tissue in nine obese, glucose-intolerant subjects and 13 non- obese subjects of similar age and sex, 2. Compared with non-obese subj ects, the forearm of the obese subjects was resistant to insulin stimu lation of glucose uptake after a mixed meal, In contrast, adipose tiss ue showed little evidence of insulin stimulation of glucose uptake, an d adipose tissue in subjects in both normal and obese groups behaved v ery similarly (assessed per 100 g of tissue), 3. For lactate flux, adi pose tissue behaved very similarly (per 100 g of tissue) in obese and non-obese subjects, and was a consistent lactate exporter, 4. We concl ude that insulin resistance of glucose uptake observed in the forearm of obese subjects is not evident in adipose tissue, Adipose tissue glu cose uptake in obese, insulin-resistant subjects is similar to that in lean control subjects, although it occurs at elevated circulating ins ulin and glucose concentrations.