Impact of comorbid conditions and race/ethnicity on glycemic control among the US population with type 2 diabetes, 1988-1994 to 1999-2004.

OBJECTIVE: To measure trends in glycemic control in type 2 diabetes in the United States from 1988-1994 to 1999-2004 and to identify factors influencing glycemic control, including the presence of comorbid conditions and race/ethnicity.
METHODS: Participants in the National Health and Nutrition Examination Surveys (1988-1994 and 1999-2004) aged ≥30 years with diagnosed type 2 diabetes were identified. Outcome measures included glycemic control [glycosylated hemoglobin (A1C) <7%] and pharmacologic treatment rate. Comorbid conditions assessed included obesity, hyperlipidemia, and hypertension.
RESULTS: Prevalence of type 2 diabetes increased from 5.8% in 1988-1994 to 7.1% in 1999-2004. Rates of treatment for type 2 diabetes improved, from 72.3% to 82.2%. The proportion of patients who achieved A1C <7% did not change significantly (44.4% to 50.1%, P=.06); however, blood pressure and cholesterol level both improved. During 1999-2004, only 14% of persons treated for type 2 diabetes did not have an additional comorbid condition; 21% had all three comorbid conditions. During 1999-2004, among treated patients, non-Hispanic blacks were 0.43 times as likely (95% CI 0.29-0.63), and Mexican Americans were 0.47 times as likely (95% CI 0.32-0.68), to have A1C <7% compared to non-Hispanic whites.
CONCLUSIONS: Despite improved treatment rates, one in two individuals with type 2 diabetes has A1C of ≥7%. Most type 2 diabetic subjects also suffer from hypertension, hyperlipidemia, and/or obesity, and glycemic control rates were lowest for those with all three conditions. Non-Hispanic blacks and Mexican Americans are less likely to achieve glycemic control as compared to non-Hispanic whites.