[Nocturnal hypoglycemia in insulin-dependent diabetics]

Repeated hypoglycaemia has been reported to impair recognition of subsequent hypoglycaemia with a high risk of severe hypoglycaemia. This intensified insulin therapy may be dangerous in insulin-dependent diabetes mellitus (IDDM) patients with unawareness of hypoglycaemia.

We assessed the incidence of nocturnal hypoglycaemia and the benefit of an additional bedtime snack in IDDM patients treated by 2 or 3 daily injections. Capillary blood glucose was measured by finger strip at 10 p.m. and plasma venous glycaemia was determined at 0, 2, 4 and 8 a.m.

The study was composed of two phases. In the first phase, patients (n = 93) did not receive any snack at bedtime. Blood glucose fell to 2.75 mmol/l or less in 33%. Among the 40 patients with a 10 p.m. glycaemia of 9 mmol/l or less, 57.5% experienced nocturnal hypoglycaemia vs 15% of the 53 others. The second phase concerned 106 IDD patients. An additional bedtime snack was given when 10 p.m. blood glucose was 9 mmol/l or less. The incidence of hypoglycaemia fell to 32% (14 of 44 IDDM) i.e. a significant benefit of 44% (p < 0.01). However patients who received this additional bedtime snack had a slightly higher 8 a.m. glycaemia than those with 10 p.m. glycaemia at 9 mmol/l or less during the first phase (9.61 +/- 5.67 mmol/l vs 7.75 +/- 4.30 mmol/l) but this result is not significant.

Prevention of nocturnal hypoglycaemia may be achieved in IDDM patients by bedtime glucose determination and an additional snack when glycaemia is 9 mmol/l or less.