Admission plasma glucose and diabetes mellitus in elderly admissions to hospital

Over 6 months, all admissions to three geriatric wards were studied to define an admission plasma glucose level (APG) that identified previously undiagnosed diabetes mellitus. Subjects with APG greater than or equal to 7.0 mmol l(-1) had a modified oral glucose tolerance test (OGTT) when well before discharge if their dose of steroid and/or thiazide was constant, and they were neither terminally ill nor dead; excluded were 1 subject on reducing steroid doses, and 9 moribund admissions without APG. If the first 2 h OGTT result was greater than or equal to 11.1 mmol l(-1), a second OGTT was performed 6 weeks later to fulfil 1985 WHO criteria. Subjects with APG < 7.0 mmol l(-1) did not have OGTT. Seventy had a previous diagnosis of diabetes; scrutiny of records and OGTT refuted the diagnosis in 5, who were excluded from further analysis. Diabetes was only commonly found among those with APG greater than or equal to 8.0 mmol l(-1), and the proportion was small until APG greater than or equal to 13 mmol l(-1), although even then only 47 % (95 % CI 21-73 %) had diabetes. Fourteen of 28 subjects with initial OGTT results suggesting diabetes were not diabetic on retesting. Inpatient mortality was higher if APG greater than or equal to 7.0 (Odds ratio 2.82; CI 1.63-4.89) or the subject had known diabetes (Odds ratio 2.43; CI 1.15-4.97) compared to APG < 7; there was no age or sex difference between these three groups. We conclude that, unless overtly diabetic, diagnosis of diabetes in elderly medical admissions needs later confirmation. (C) 1997 by John Wiley & Sons, Ltd.