No abstract

Brain-derived natriuretic peptide (BNP) is a cardioprotective peptide released, together with the inactive NH(2)-terminal part of its prohormone (NT-pro-BNP), in response to different kinds of myocardial stress. Hypoglycemia and hypoxemia are conditions that threaten cellular function and hence potentially stimulate BNP release. BNP interacts with the renin-angiotensin system (RAS). The aim of this study was, therefore, to explore if basal RAS activity has an impact on NT-pro-BNP concentrations during myocardial stress induced by hypoglycemia and hypoxemia. From a cohort of 303 healthy young men, 10 subjects with high-RAS activity and 10 subjects with low-RAS activity (age 26 +/- 1 yr; mean +/- SE) were studied in a single-blinded, randomized, counterbalanced, crossover study on three occasions separated by at least 3 wk: 1) hypoglycemia (mean nadir plasma glucose 2.7 +/- 0.5 mmol/l), 2) hypoxemia (mean nadir Po(2) 5.8 +/- 0.5 kPa), and 3) normoglycemic normoxia (control). NT-pro-BNP was measured at baseline, during the stimuli, and in the recovery phase. Hypoxemia was associated with a 9% increase in NT-pro-BNP from 2.2 +/- 1.5 pmol/l at baseline to 2.4 +/- 1.5 pmol/l during hypoxemia (P < 0.001). Hypoglycemia did not affect the NT-pro-BNP level. RAS activity had no impact on NT-pro-BNP levels during hypoglycemia and hypoxemia. Hypoxemia, but not hypoglycemia, stimulates NT-pro-BNP. This indicates that cardiac defense mechanisms against hypoglycemia, if any, are probably different from those against hypoxemia. Basal RAS activity had no impact on NT-pro-BNP levels.

Low basal RAS activity may be associated with a slightly more pronounced QT prolongation during hypoglycaemia, when compared with high RAS activity. The impact, however, is modest and the clinical consequence is unclear.

Aim: To compare self-treatment of mild symptomatic hypoglycaemia in people with type 1 diabetes with national Danish guidelines recommending 10-20 g of refined carbohydrate initially followed by unrefined carbohydrates. Methods: A cohort of 201 patients with type 1 diabetes filled in a questionnaire including self-treatment of mild symptomatic hypoglycaemia and occurrence of mild and severe hypoglycaemia. Initial intake of less than 10 g of refined carbohydrate was defined as under treatment and intake of 20 g or more as over treatment. Results: A total of 147 patients (73%) answered both questions about initial and follow-up self-treatment of hypoglycaemia. Fifty per cent of patients treated themselves with 10-20 g refined carbohydrates (female:male = 59%:43%; p<0.05), whereas 37% over treated (female:male = 34%:39%; not significant) and 13% under treated (female:male = 6%:18%; p<0.05). Initial treatment was followed by consumption of unrefined carbohydrates in 70% of the patients. Overall, 37% (female:male = 49%:28%; p<0.05) of the patients adhered to guidelines. The number of severe hypoglycaemic episodes (lifetime) and amount of carbohydrate intake were positively correlated (r=0.2; p<0.05). Adherence to guidelines was not related to occurrence of mild and severe (in the last year) hypoglycaemia, glycated haemoglobin, or fear of hypoglycaemia. Conclusions: Only about one-third of patients with type 1 diabetes treat mild hypoglycaemia according to guidelines. Female patients show better compliance. Patients with frequent episodes of severe hypoglycaemia over treat more often.

Basal RAS activity has significant impact on QT dynamics, but not the corrected QT interval, during recovery from hypoglycaemia and hypoxaemia. The impact, however, is modest and more subtle than initially expected. The clinical relevance is unclear.