According to the new diagnostic criteria (i e, fasting plasma glucose (FPG)≥7.0mmol/L(≥126mg/dl)) as suggested recently by the WHO expert committee on the diagnosis and classification of diabetes mellitus (DM), the diagnostic level of FPG in a Chinese diabetic population was explored.

From 250 000 subjects, age≥25 years studied in a national DM epidemiologic surveyB Bin 1994, 13 211 subjects who received 75g oral glucose tolerance test (OGTT) were analyzed, including 2 380 subjects with newly diagnosed type 2 DM(NDM), 3 106 subjects with impaired glucose tolerance (IGT) and 7725 subjects with normal glucose tolerance.

The FPG distribution frequency in the NDM group showed that 50% of subjects had FPG< 7.8mmol/L. Using linear regression model to compare the relation of FPG to 2-h plasma glucose after OGTT (PG2h) in NDM group, it was found that FPG correlating most to PG2h≥11.1mmol/L(≥200mg/dl) was≥6.7mmol/L(≥ 121mg/dl) (P <0.0001). It was quite close to FPG≥7.0mmol/L as suggsted by WHO. The specificity in FPG≥7.0mmol/L was higherthan in FPG≥6.7mmol/L (95% and 91 % respectively) and the sensitivity in FPG≥7.0mmol/L was better than in FPG≥7.8mmol/L (67% and 53% respectively). Using multiple linear regression analysis to compare the relation of FPG to PG2h in the general subject group (n=13 211), the FPG corresponding to PG2h<7.8mmol/L was <5.9 mmol/L(< 107mg/dl).

FPG≥7.8mmol/L is not a sensitive diagnostic criterion of DM. FPG≥7mmol/L, due to its high specificity and better sensitivity than FPG≥7.8mmol/L, can be accepted as a diagnostic criterion of DM. At the same time, WHO suggests that FPG< 6.1 mmol/L as a dividing point between normal and IGT can cooperate with PG2h<7.8mmol/L and is likewise suitable to the population in China.

Plasma glucose; OGTT; Diabetes mellitus