Long term instability of fasting plasma glucose predicts mortality in elderly NIDDM patients. The Verona Diabetes study

The aim of this study was to evaluate whether long-term glucose control, as assessed by fasting plasma glucose determinations during 3 years, is a predictor of all-cause mortality in elderly NIDDM patients. Five hundred and sixty-six NIDDM patients attending the Verona Diabetes Clinic, aged 75 years and over, were followed-up from 1 January 1987 to 31 December 1991 to assess all-cause mortality. From their clinical records all fasting plasma glucose determinations available for the years 1984 to 1986 were collected and analysed. Patients were grouped in tertiles according to mean (M-FPG), coefficient of variation (CV-FPG) and trend over time (slope, S-FPG) of fasting plasma glucose during the period of retrospective evaluation. Mortality was assessed by observed/expected ratios, univariate Kaplan-Meier survival analysis and multivariate Poisson regression model. By 31 December 1991, 61 men and 127 women had died. Increased observed/expected ratios were found in women from the top M-FPG tertile, in patients (men and women) from the top CV-FPG tertile and in patients with a S-FPG less than -0.30 mmol/l per year (lowest tertile). Patients in the lowest tertile of CV-FPG and in the middle tertile of S-FPG had a reduced mortality risk. Kaplan-Meier survival analysis indicated that patients with high CV-FPG as well as those in tertiles I and III of S-FPG (i.e., those with a definitely negative or definitely positive slope) had an increased probability of dying, without any significant differences between the three tertiles of M-FPG