The Characteristics Of Patients With Pre-diabetes And The Conversion Study

Impaired glucose regulation (IGR) includes impaired fasting glucose (IFG) and impaired glucose tolerance (IGT), which belong to the intermediate state between normal glucose tolerance (NGT) and diabetes mellitus, and IGR is also called "pre-diabetic state".In this study, a total of 1577 middle-aged or aged adults living in Beijing who were excluded from diabetes mellitus by 75g oral glucose tolerance test (OGTT), answered the questionnaire and completed physical examination, were included for the analysis of the rationality of lower cut point of fasting plasma glucose (FPG) for the diagnosis of IFG and the comparison of clinical characteristics of different component of IGR. And a total of 613 adults with IGR and 200 adults with NGT were included for the analysis of the islet beta cell function and the insulin resistance. There were 463 adults who were diagnosed as having IGR at baseline were followed up after one year's health education to analyze the outcome and influence factors . Then a total of 169 adults who reverted to NGT at the first year were followed up at the second year to investigate the natural outcome.This study showed that if OGTT 2h plasma glucose (2hPG) was referred as the diagnostic criteria of IGR, 5.5mmol/L was the optimal cut point of FPG. By the criteria of ADA 2003, with increasing of age, the constituent ratio of NGT decreased significantly (P<0.05 ), I-IGT increased significantly (P<0.05 ). In the I-IFG population, the ratio of males was slightly higher than females, while in the I-IGT population, the ratio of females was slightly higher (P>0.05 ) . Logistic stepwise regression analysis showed that age, waist circumference, serum triglyceride (TG), total cholesterol (TC) and systolic blood pressure (SBP) were all the independent risk factors of IGR.In I-IFG group, HOMA-IR was significantly higher than NGT and I-IGT group ( P<0.05 ) , ISI-Stumvoll was lower than NGT group, but higher than I-IGT group ( P<0.05 ); ISI, HBCI/IR and FBCI/IR were significantly lower than the two groups ( P<0.05 ). In I-IGT group, HOMA-IR, ISI, HBCI/IR and FBCI/IR were between NGT group and I-IFG group; ISI-Stumvoll, the first and second phase insulin secretion index, â–³I₁₂₀/â–³G₁₂₀ and â–³I₁₂₀/â–³G₁₂₀/IR were significantly lower than NGT group and I-IFG group (P<0.05 ) . In the IFG/IGT group, HOMA-IR was the highest among all the groups, and ISI was the lowest, ISI-Stumvoll was lower than the NGT group and the I-IFG group ( P<0.05 ) ; the first and second phase insulin secretion index, â–³I₁₂₀/â–³G₁₂₀ and â–³I₁₂₀/â–³G₁₂₀/IR were the lowest among all the groups ( P<0.05 ) . In the non-diabetic population, with the increasing of FPG and 2hPG, HOMA-IR increased gradually, and ISI, ISI-Stumvoll, HBCI/IR, FBCI/IR, the first and second phase insulin secretion index and â–³I₁₂₀/â–³G₁₂₀/IR decreased gradually ( P<0.05 ) .Among 463 IGR patients, there were 212 (45.8%) who reverted to NGT after a year, and 233 (50.3%) remained IGR, and 18 (3.9%) progressed into diabetes mellitus. In those who reverted from IGR to NGT, FPG, fasting plasma insulin (FINS), 2hPG, OGTT 2h insulin (2hINS) and HOMA-IR were decreased significantly, and HBCI/IR, â–³I₁₂₀/â–³G₁₂₀/IR increased significantly (P<0.05). Logistic multi-regression analysis showed that waist circumference, FPG, 2hPG, HOMA-IR were negatively related to the reversion of IGR to NGT in the males; while in the females, TG, FPG were negatively related to the reversion of IGR to NGT, and HBCI/IR was positively related to the reversion of IGR to NGT. A total of 190 of those who reverted to NGT were followed up at the second year, 53.3% of them maintained to be NGT, 45.6% transformed into IGR, and 1.2% progressed into diabetes mellitus. In IGR→NGT→NGT group, the ratio of elevated TG, elevated FPG, more than two metabolic abnormities and metabolic syndrome (MS) at baseline were significantly lower than in the IGR→NGT→IGR group( p<0.05 ). At the second year, the ratio of elevated waist circumference, elevated bloodpressure, elevated TG, reduced high density lipoprotein cholesterol (HDL-c), elevated FPG, more than two metabolic abnormities and MS at the second year were significantly lower than in the IGR→NGT→IGR group (p<0.05 ) .In conclusion, the down-regulation of FPG cut point for the diagnosis of IFG had its rationality. With increasing of age, the ratio of NGT decreased, and the ratio of IGR increased, especially I-IGT. I-IFG was more common in the male, while I-IGT was more common in the female. Age, waist circumference, TG, TC, and SBP were the independent risk factors of IGR.I-IFG had severe hepatic insulin resistance and basal islet beta cell dysfunction. I-IGT had marked peripheral insulin resistance and severe after-glucose-loading beta cell dysfunction. IFG/IGT had more severe insulin resistance and beta cell dysfunction than I-IFG and I-IGT. When FPG <7.0mmol/L, and 2hPG < 11.1mmol/L, FPG and 2hPG were positively correlated with insulin resistance, while they were negatively correlated with islet beta cell dysfunction.The improvement of glucose regulation was in good accordance with the improvement of insulin resistance and pancreatic beta-cell function. FPG, TG, waist circumferences, insulin resistance and beta-cell function were all influence factors for the reversion of IGR to NGT. Those with less metabolic abnormalities at baseline and with more obvious improvement would be more likely to revert to and maintain NGT.