[Estimation of the normal range of blood glucose in rats]

To evaluate the distribution and affecting factors of blood glucose in normal rats for the criterion of hyperglycemia in animal model.

The data of fast blood glucose (FBG) and 120 min postprandial blood glucose (PBG) of nearly 500 Wistar and SD rats from different experiment in our laboratory were collected and analyzed by multi-variable analysis and optimal scaling regression for the distribution and key affecting factors of blood glucose. Comparing the blood glucose determined by different method (glucose oxidase method or glucose monitor with strips), different duration (fasting for 5 h or 11 h), different blood source (from abdominal aorta or tail), and different time for separating serum after sampling (at once or till 120 min) was conducted in another 40-100 Wistar rats. A mathematical model for the contribution of different components was evaluated and combined by parameters of half width and range.

The average FBG and PBG of normal Wistar rats was (3.95 +/- 1.31) mmol/L and (5.65 +/- 1.63) mmol/L, and the 95% upper limit was 6.2 mmol/L and 7.9 mmol/L respectively. The differences of fasting duration, sample source, time before separating serum and testing methods, excepting for rat species, were significant (P < 0.05). The results showed that the blood glucose tested by glucose monitor method was not comparable with GOD method while the range of blood glucose was out of 7-11 mmol/L. The difference of blood glucose between fasting for 5h and 11 h was 0.8 mmol/L. Blood glucose from abdominal aorta was 40% higher than that from tail. The reduction of blood glucose was 8% in 60 min and over 50% in 120 min after blood being sampled. After the test requirement being regulated, the upper limit for FBG and PBG was expanded to 7.5 mmol/L and 10.4 mmol/L, respectively.

The onset of diabetics in rat is judged as blood glucose being higher than the expanded normal upper level. The criteria for rats are close to that for human.