Objective: To evaluate the metabolic profiles of insulin secretion and insulin sensitivity in different categories of nondiabetic patients with essential hypertension, we made a retrospecting study in our hospital.
Methods: According to the criteria of WHO and ADA, we calculated the distribution of plasma glucose levels during a 75 g oral glucose tolerance test (OGTT). Nondiabetic subjects with hypertension were classified into the following four groups: (1) normal glucose tolerance (NGT) with fasting plasma glucose (FPG) < 6.1 mmol/L and 2h-plasma glucose (2hPG) < 7.8 mmol/L, (2) Isolate impaired fasting glucose (IFG) with FPG 6.1-7 mmol/L and 2hPG < 7.8 mmol/L, (3) Isolate impaired glucose tolerance (IGT) with FPG < 6.1 mmol/L and 2hBG 7.8-11.1 mmol/L, (4) impaired fasting glucose and impaired glucose tolerance (IFG/IGT) with FPG 6.1-7 mmol/L and 2hBG 7.8-11.1 mmol/L. Then we divided the groups of NGT and IGT based on the normal 30 or 60 minute plasma glucose level during OGTT respectively. 30 minute plasma glucose level < 11.1 mmol/L and 60 minute plasma glucose level < 10.5 mmol/L were considered to be normal. HOMA-IR (insulin resistance) and composite ISI (insulin sensitivity index) were used to estimate insulin resistance and HOMA-beta and DeltaI/DeltaG index to estimate insulin secretion.
Results: 11.1% of the 1193 subjects were newly diagnosed diabetic patients, in whom 57.9% had isolated postchallenge hyperglycemia only. In the IGT and IFG/IGT groups, HOMA-IR were significantly higher than that in the NGT group, whereas composite ISI and DeltaI/DeltaG were significantly lower than that in the NGT group. Whether 30 or 60 minute plasma glucose level was high or not, composite ISI in IGT group was significantly lower than that in the NGT group. In the NGT group, DeltaI/DeltaG in subjects with high 30 or and 60 minute plasma glucose level was significantly lower than that in subjects with normal 30 and 60 minute plasma glucose level.
Conclusions: Subjects with IGT or IFG/IGT have both impaired insulin sensitivity and insulin secretion. In the NGT group, subjects with high 30 or/and 60 minute plasma glucose level have impaired beta-cell function.