The Influence of Self-monitoring Blood Glucose Frequency on the Oscillation of Hemoglobin A1c and Chronic Complications

Background: A fluctuating blood glucose level is one of the risks of chronic complicationsin diabetes. Previous studies indicated that hemoglobin A1c (HbA1c) valuesappa r ent ly improved a f t e r ini t i a t ion of s e l f -moni tor ing blood glucos e(SMBG). The purpose of this study is to investigate the relationship betweenthe frequency of SMBG, long-term fluctuatation of HbA1c, and risks ofchronic complications in diabetes.Methods: We enrolled 1052 patients with type 2 diabetes. The mean follow-up was 4.7years. The HbA1c level and frequency of SMBG were recorded every 3months. Non-mydriatic retinal photography, semiquantitative neuropathyassessment, the lipid profile, serum creatinine level, and urine protein weremeasured at the beginning of the study and then every year. The fluctuationin HbA1c throughout the period was expressed as the standard deviations(SDs) of all measurements of the HbA1c.Results: The frequency of SMBG was significantly and negatively correlated with theSDs of the HbA1c (r = –0.553, p < 0.001) but not with the average HbA1c.After controlling for age, sex, body mass index, duration of diabetes andcomorbidities (dyslipidemia and hypertension), the correlation was stillapparent (r = –0.511, p = 0.008). Patients with progression of nephropathy,neuropathy, and retinopathy, exhibited greater fluctuation of HbA1cs (2.38 0.99 vs. 0.93 1.16, p-value 0.002; 0.97 1.59 vs. 0.90 0.56, pvalue 0.04; 0.99 1.33 vs. 0.90 0.56, p-value 0.04, respectively) and lessfrequent SMBG (3.2 2.6 vs. 4.3 3.1, p-value 0.02; 3.2 2.6 vs. 4.1 3.9, p-value 0.05; 3.0 3.1 vs. 4.2 2.8, p-value 0.01, respectively) thanpatients without progression of these complications.Conclusion: This study shows that frequent SMBG decreased the fluctuation of HbA1cand decreased microvascular complications. Decreasing fluctuation ofHbA1c may play an important role in diabetes treatment.