Neuromuscular blocking activity of tubocurarine in patients with diabetes mellitus.

Previous clinical reports have suggested that deep tendon reflexes of diabetic patients are delayed and experimental studies have reported differential sensitivity of motor endplates to neuromuscular blocking drugs. These observations prompted us to study the neuromuscular effect of tubocurarine in 25 diabetic and 15 non-diabetic patients during urological surgery. Anaesthesia was induced with thiopentone followed by suxamethonium and maintained with nitrous oxide in oxygen and increments of butorphanol. Muscle relaxation was provided with tubocurarine in an initial dose of 0.25 mg kg-1 and increments of 20% of the initial dose. At the end of surgery, residual neuromuscular block was antagonized with increments of neostigmine 0.5 mg and atropine 0.2 mg. There was a delay in the onset of action of tubocurarine in diabetic patients. A no-response state was obtained in some patients, and its duration correlated with post-tetanic count (PTC) in diabetic patients, and with post-tetanic twitch height percent (PTTH%) in the control group. We concluded that, in diabetic patients, the onset of action of tubocurarine was delayed compared with control patients, and the reliable predictor of the duration of the no-response time was PTC in diabetic patients and PTTH% in non-diabetic subjects.