RESUMO
BACKGROUND AND OBJECTIVE: To assess the relevance of unrecognised hyperglycaemia among high-risk subjects for developing type 2 diabetes. SUBJECTS AND METHOD: Cross-sectional multicentre study in primary care. Subjects aged 40 to 75 years with previous evidence of impaired glucose metabolism were screened according to the World Health Organization rules by means of an oral glucose tolerance test (OGTT). Those with diabetes diagnostic criteria were excluded. An individualized 48-h ambulatory continuous glucose monitoring (CGM) calibrated by plasma values (Glucoday) was performed. Data from biosensor activity were computerized in order to identify hyperglycaemic records. RESULTS: 50 out of 64 screened subjects were included and evaluated; there were 30 female (60%). Mean age was 59 years; body mass index, 30.9; HbA1c, 5.3%, and HOMA, 2.8. Regarding the CGM results, 9 whole registers (18%) were rejected because of technical problems and 41 continuous profiles (72%) were analysed, corresponding to 17 (41.5%) subjects with normal OGTT and 24 (58.5%) with non-diabetic hyperglycaemia on OGTT. Mean CGM time with hyperglycaemia (fasting > or = 6.1 mmol/l or non-fasting > or = 7.8 mmol/l) accounted for 5.8 h, a 17.2% of the effective register per subject (33.8 h). Both groups matched the World Health Organization diabetes diagnostic interval (fasting > or = 7 mmol/l or non-fasting > or = 11.1 mmol/l): 1.1 h of effective register (3.6%) and 1.2 h (3.3%), respectively. CONCLUSIONS: The CGM evidenced a high degree of unrecognised hyperglycaemia among high-risk individuals. Therefore, casual plasma glucose measurements should be recommended to achieve early screening.