Introduction Targeting better glycated hemoglobin (HbA1c) and blood pressure (BP) goals may endanger older adults with type 2 diabetes mellitus (T2DM). Overtreatment of T2DM and hypertension is a trending issue, although undertreatment is still common. We investigated the rates and predictors of overtreatment and undertreatment of glycemia and BP in older adults with T2DM and physicians' attitudes to deintensify or intensify treatment. Methods Data from older adults (>= 65 years) enrolled in a large nationwide T2DM survey in 2017 across Turkey were analyzed. Overtreatment of glycemia was defined as HbA1c < 6.5% plus the use of >= 2 oral antihyperglycemics or insulin, and BP overtreatment was defined as systolic BP (SBP) < 120 mmHg or diastolic BP (DBP) < 65 mmHg plus the use of >= 2 drugs. Undertreatment of glycemia was defined as HbA1c > 9%, and BP undertreatment was defined as SBP > 150 mmHg or DBP > 90 mmHg. Deintensification or intensification rates were calculated according to treatment modification initiated by the treating physician(s). Results The rate of overtreatment in the glycemia group (n = 1264) was 9.8% (n = 124) and that in the BP group (n = 1052) was 7.3% (n = 77), whereas the rate of undertreatment was 14.2% (n = 180) and 15.2% (n = 160), respectively. In the adjusted model, use of oral secretagogues (sulfonylureas or glinides) (odds ratio [OR] 1.94, 95% confidence interval [CI] 1.2-3.1) and follow-up at a private clinic (OR 1.81, 95% CI 1.0-3.3) were predictors of glycemia overtreatment. BP overtreatment was independently associated with the use insulin-based diabetes therapies (OR 1.86, 95% CI 1.14-3.04). There was no independent association of BP undertreatment to the study confounders. The deintensification and intensification rates were 25 and 75.6%, respectively, for glycemia and 10.9 and 9.2%, respectively, for BP. Conclusions The results show that one in ten older adults with T2DM are overtreated while one in four require modification of their current antihyperglycemic and antihypertensive treatments. Physicians are eager to intensify medications while they largely ignore deintensification in diabetes management. These results warrant enforced measures to improve the care of older adults with T2DM. Plain Language Summary Plain language summary is available for this article.