Blood glucose not hemoglobin influenced glycosylated hemoglobin in type 2 diabetes patients on plateau of China

To investigate the correlation between glycosylated hemoglobin (HbA_1C) levels and fasting blood glucose (FBG), 2-hour postprandial blood glucose (PBG2h) and hemoglobin (Hb) levels, and to evaluate the factors influencing HbA_1C level as well as the effects of Hb variations on blood glucose and HbA_1C levels. 208 patients with type 2 diabetes (T2DM) who resided at an altitude of 1,900 m in Kunming city, China for over 5 years and received oral anti diabetic drugs without adjustments for over 3 months were enrolled. Venous blood was sampled for FBG and PBG2h assays, as well as HbA_1C and Hb analyses at three different time points. HbA_1C levels were plotted with FBG, PBG2h and Hb levels, and their correlation was evaluated using Pearson’s correlation analysis and regression analysis. The levels of FBG, PBG2h and HbA_1C were compared between patients with high and normal Hb levels. There was significant positive linear correlation between HbA_1C levels and FBG levels (R² = 0.87, P < 0.001), as well as PBG2h levels (R² = 0.89, P < 0.001). The regression equation of HbA_1C with FBG (x₁) and PBG2h (x₂) was y = 1.124 + 0.334x₁ + 0.284x₂. There was no strong correlation between HbA_1C levels and Hb levels. No significant differences were observed in FBG, PBG2h and HbA_1C levels between patients with high and normal Hb levels. FBG and PBG2h are the main factors influencing HbA_1C levels in patients with T2DM, whereas Hb levels have no significant effects on FBG, PBG2h and HbA_1C levels.