According to the above methods and analyses, the following categorical variables were entered in a backward stepwise logistic regression analysis: sex; age ≥ 75 years; body mass index (BMI) < 25; COPD; bronchiectasis; hypertension; CHD; cerebral infarction; renal failure; hemopathy; cancer; treatment of DM; use of insulin; duration of DM ≥ 20 years; HbA1c ≥ 9%; FBG ≥ 10 mmol/L; and PBG ≥ 13 mmol/L (Table 2). Here, INS is linked to chronic obstructive pulmonary disease.