Muscle metabolism and quality (MQI) in prediabetic sedentary man

Twelve pairs of healthy sedentary males matched for their body mass index (BMI) with either a low insulin response (LIR; a stage of prediabetes) or a high (HIR; controls) to a standardized glucose infusion test (GIT) were studied in respect to their exercise capacities (W_OBLA, W_SL and relative W_OBLA: W_OBLA × W_SL-1 × 100), muscle fiber composition (%ST), muscle citrate synthase activity (CS), muscle ubiquinone (MUQ), MUQ over %ST (muscle quality index, MQI), and peripheral insulin sensitivity (PIS) as described with insulin-clamp techniques (SIGITmean). LIR and HIR displayed normal PIS and positive relationships versus exercise capacity. LIR's but not HIR's relative W_OBLA was related to CS as earlier only documented in endurance athletes but at a lower level than both in HIR and athletes. This pointed at a poor peripheral oxygen delivery in LIR. LIR's MQI decreased relative to HIR's the higher the muscle CS indicating radical related muscle trauma in LIR as in athletes. LIR representing prediabetes described muscle anomalies, which could represent prestages of the lesions observed in type-2 diabetes. They are claimed to be responsible for insulin-, glucose-, lipid-resistance, and peripheral circulatory resistance.