Higher systolic blood pressure is specifically associated with better islet beta-cell function in T2DM patients with high glycemic level

Abstract

Abstract Background Patients with type 2 diabetes mellitus (T2DM) usually have high blood viscosity, which could decrease blood supply to the pancreas. Increased blood pressure (BP) has been reported as a potentially compensatory response to the maintenance of islet blood perfusion. However, the influence of BP on beta-cell function in people with diabetes remains inconsistent. This study aimed to examine the relationship between BP and beta-cell function in patients with T2DM under different HbA1c levels. Methods This cross-sectional study included 615 T2DM patients. Clinical data were extracted from hospital medical records. Beta-cell function was assessed with insulin secretion-sensitivity index-2 (ISSI2). Multivariable linear regression analysis and restricted cubic splines (RCS) analysis were performed to identify the association between systolic blood pressure (SBP) and ISSI2. Mediation analysis was performed to determine whether higher SBP could reduce blood glucose by enhancing beta-cell function. Results After adjustment of age, sex, duration of diabetes, blood lipids, Matsuda index, and drug treatment, in participants with HbA1c ≥10%, SBP was positively associated with log ISSI2 (b = 0.044, 95%CI: 0.011, 0.078), and the SBP between 140 to150 mmHg had the highest log ISSI2 (b = 0.306, 95%CI: 0.126, 0.485). RCS analyses further demonstrated an inverted U-shaped association between SBP and ISSI2 with the SBP at 146 mmHg corresponding to the best beta-cell function. Additionally, higher SBP was “paradoxically” associated with lower 2h postprandial blood glucose (PBG) when SBP < 150mmHg, which was almost exclusively mediated by ISSI2 (mediating effect=-0.057, 95%CI: -0.085, -0.029). However, SBP was not associated with ISSI2 and 2h PBG in participants with HbA1c < 10%. Conclusions A certain degree of elevated SBP (140–150 mmHg) was associated with better beta-cell function and reduced 2h PBG in T2DM patients with HbA1c ≥10% but not in those with HbA1c < 10%. T2DM patients with unfavorable glycemic control may benefit from higher SBP through enhanced islet beta-cell function.