Aims <p>Underestimating hyper-/hypoglycemia or failure to perceive hyperglycemia hinders optimal glucose management in diabetes care. Our study investigated individuals who, while aware of their hyper-/hypoglycemia, may not perceive them as problematic. Also, we clarified the factors contributing to discrepancies between these individuals' perceptions and the objective measurements.</p> Materials and methods <p>This study was a prospective observational study comprising 284 Japanese individuals with type 2 diabetes who underwent ambulatory blinded professional continuous glucose monitoring (CGM) and self-administered the Diabetes Treatment Satisfaction Questionnaire (DTSQ). Individuals with a time above range (TAR; &gt; 180&#xa0;mg/dL) ≥ 25% and those who answered 0 (“never”) or + 1 (“almost never”) for the frequency of hyperglycemia in the DTSQ were defined as having no-perception of hyperglycemia. Individuals with a time below range (TBR; &lt; 70&#xa0;mg/dL) ≥ 4% with an answer of 0 or + 1 for the frequency of hypoglycemia were labeled as having no-perception of hypoglycemia. Multivariate logistic regression analysis was performed to analyze clinical characteristics associated with the discrepancies between failure to perceive hyper-/hypoglycemia and TAR ≥ 25% or TBR ≥ 4%.</p> Results <p>Insulin-use (odds ratio [OR] = 0.29, <i>p</i> &lt; 0.05) and older age (OR = 1.05, <i>p</i> &lt; 0.05) were independent determinants of no-perception of hyperglycemia. Low eGFR was an independent determinant of no-perception of hypoglycemia (OR = 0.94, <i>p</i> &lt; 0.05).</p> Conclusions <p>No-insulin-use, being an older adult, and renal dysfunction are linked to the discrepancy between the perception of hyper-/hypoglycemia and actual blood glucose. These results will help create personalized diabetes care.</p>