空腹血糖水平与胰岛素抵抗的关系

目的探讨美国糖尿病协会2003年修订的空腹血糖受损(IFG)下限新切点(5·6mmol/L)划分出的中国血糖调节异常(IGR)者是否存在胰岛素抵抗。方法选取糖调节正常者(NGR)9例;以新标准划分的单纯IFG者9例;空腹及糖负荷后血糖均异常的糖调节受损者共20例,其中以新空腹血糖(FPG)切点划分的新联合糖耐量低减(IGT)者10例;以旧FPG切点划分的旧联合IGT者10例;2型糖尿病患者10例。以高胰岛素正葡萄糖钳夹技术测定受试对象的胰岛素敏感性,以静脉葡萄糖耐量试验评估其胰岛β细胞分泌功能。结果(1)新单纯IFG组、新联合IGT组和旧联合IGT组的葡萄糖输注率(GIR)分别为(7·2±0·8、7·0±1·5、4·8±0·4)mg·kg-1·min-1]明显低于NGR组(10·3±0·9)mg·kg-1·min-1,P值均<0·05];旧IGT组和DM组(5·6±1·0)mg·kg-1·min-1]处于相近水平。(2)空腹胰岛素水平在所有IGR组均升高,在DM组下降。(3)新IFG组的胰岛素一、二相分泌量和NGR组相似,但随糖代谢紊乱程度加重,胰岛素一相分泌量进行性下降,而二相分泌水平先逐渐升高,后有所降低。结论(1)新空腹血糖切点划分出的中国IGR者已经出现胰岛素抵抗。(2)随糖代谢紊乱程度的加重,胰岛素分泌缺陷趋于明显。

The relation between fasting plasma glucose concentrations and insulin resistance

OBJECTIVE: To study whether insulin resistance exists in the Chinese individuals with impaired glucose regulation (IGR) defined by the modified cut-point value (5.6 mmol/L) in 2003 version of ADA criteria for impaired fasting glucose (IFG). METHODS: We selected 9 persons aged (44 +/- 5) years, body mass index (BMI) (24.0 +/- 0.8) kg/m(2)] with normal glucose regulation NGR, fasting plasma glucose (FPG) < 5.6 mmol/L, plasma glucose-2h (PG2h) < 7.8 mmol/L], 9 aged (49 +/- 3) years, BMI (29.0 +/- 0.8) kg/m(2)] with isolated IFG defined by the new criteria (n-i-IFG, FPG < 5.6 mmol/L, PG2h < 7.8 mmol/L), 20 with combined impaired glucose tolerance (c-IGT) including 10 aged (45 +/- 4) years, BMI (26.0 +/- 1.3) kg/m(2)] defined by the new criteria (n-c-IGT, FPG 5.6 - 6.0 mmol/L, PG2 h 7.8 - 11.0 mmol/L) and 10 aged (49 +/- 3) years, BMI (27.0 +/- 1.1) kg/m(2)] defined by the old criteria (o-c-IGT, FPG 6.1 - 6.9 mmol/L, PG2h 7.8 - 11.0 mmol/L), 10 aged (43 +/- 5) years, BMI (29.0 +/- 2.8) kg/m(2)] with type 2 diabetes mellitus (DM). Insulin resistance of the subjects was measured by using hyperinsulin-euglycemic clamp in which the glucose infusion rate (GIR) was the major index. Beta-cell function was assessed by intravenous glucose tolerance test. The DM patients only underwent the hyperinsulin-euglycemic clamp. RESULTS: (1) The GIR of n-i-IFG group and n-c-IGT group was significantly lower than that of the NGR group (7.2 +/- 0.8), (7.0 +/- 1.5) vs (10.3 +/- 0.9) mg.kg(-1).min(-1), P < 0.05]. The GIR of o-c-IGT group was the least (4.8 +/- 0.4) mg.kg(-1).min(-1)], which was similar to that of the DM group (5.6 +/- 1.0) mg.kg(-1).min(-1)], the GIR of the two groups was significantly reduced compared with the NGR goup (4.8 +/- 0.4), (5.6 +/- 1.0) vs (10.3 +/- 0.9) mg.kg(-1).min(-1), P < 0.01]. (2) As compared with the NGR group, the fasting insulin level was increased in all the IGR groups and was decreased in the DM group. (3) The first phase of insulin secretion were similar in NGR and n-i-IFG group (37.0 +/- 8.6) vs (31.7 +/- 9.2) mU/L, P > 0.05], and the n-i-IFG group had greater amount than the n-c-IGT group (31.7 +/- 9.2) vs (25.9 +/- 9.8) mU/L, P > 0.05]. But it was the least in the o-c-IGT group that significantly less than the NGR group (17.2 +/- 4.8) vs (37.0 +/- 8.6) mU/L, P < 0.05]. As compared with the NGR group, the second phase of insulin secretion was slightly increased in the n-i-IFG group (16.6 +/- 2.9) vs (21.9 +/- 3.6) mU/L, P > 0.05], and was even greater in the n-c-IGT group (16.6 +/- 2.9) vs (38.7 +/- 13.7) mU/L, P < 0.05]. But it was reduced in the o-c-IGT group (20.7 +/- 2.9) mU/L]. CONCLUSIONS: (1) The IGR subjects defined by the new cut-point value already has insulin resistance. (2) Deficit in insulin secretion is worsening as the IGR deteriorates.