Background: The aim of the present study was to determine the clinical characteristics of patients with type 2 diabetes mellitus (T2DM) treated with basal insulin who achieved an adequate fasting plasma glucose (FPG) level (<130 mg/dL), but were unable to achieve the HbA1c target (<7%; <53 mmol/mol). Methods: A cross-sectional study was performed on T2DM patients aged 31-90 years treated with basal insulin registered in the SIDIAP Q primary healthcare electronic database during 2010. Results: In 2010, of a population of 126 811 T2DM subjects, 9899 were treated with basal insulin (neutral protamine Hagedorn [NPH], detemir, or glargine). Of these, 23.5% (n = 2322) achieved optimal FPG control levels (<130 mg/dL) but an inadequate HbA1c target (>7%). Mean HbA1c values in the contolled and uncontrolled groups were 8.15% (65.6 mmol/mol) and 6.31% (45.5 mmol/mol), respectively. Patients with controlled FPG but uncontrolled HbA1c had longer T2DM duration (11.6 vs 9.9 years), higher systolic blood pressure (138.2 vs 136.3 mmHg) and low-density lipoprotein cholesterol (104 vs 99 mg /dL), and a higher prevalence of retinopathy (24.8% vs 18.2%) than patients (17.8%) with optimal control of both glycemic targets (P < 0.05). Multivariate analysis showed that inadequate glycemic control was positively related only to younger age. Conclusion: One-quarter of T2DM patients treated with basal insulin have difficulties attaining the recommended HbA1c goal despite adequate FPG levels. As some guidelines state, healthcare professionals should focus on PPG to identify and intensify treatment to control prandial glucose excursions in these patients.