HbA1c and lower-extremity amputation risk in low-income patients with diabetes.
OBJECTIVE
Diabetes confers a very high risk of lower-extremity amputation (LEA); however, few studies have assessed whether blood glucose control can reduce LEA risk among patients with diabetes, especially in practice settings where low-income patients predominate.


METHODS
We performed a prospective cohort study (2000-2009) on patients with diabetes that included 19,808 African Americans and 15,560 whites. The cohort was followed though 31 May 2012. Cox proportional hazards regression models were used to estimate the association of HbA1c with LEA risk.


RESULTS
During a mean follow-up of 6.83 years, 578 LEA incident cases were identified. The multivariable-adjusted hazard ratios of LEA associated with different levels of HbA1c at baseline (<6.0% [reference group], 6.0-6.9, 7.0-7.9, 8.0-8.9, 9.0-9.9, and ≥10.0%) were 1.00, 1.73 (95% CI 1.07-2.80), 1.65 (0.99-2.77), 1.96 (1.14-3.36), 3.02 (1.81-5.04), and 3.30 (2.10-5.20) (P trend <0.001) for African American patients with diabetes and 1.00, 1.16 (0.66-2.02), 2.28 (1.35-3.85), 2.38 (1.36-4.18), 2.99 (1.71-5.22), and 3.25 (1.98-5.33) (P trend <0.001) for white patients with diabetes, respectively. The graded positive association of HbA1c during follow-up with LEA risk was observed among both African American and white patients with diabetes (all P trend <0.001). With stratification by sex, age, smoking status, blood pressure, LDL cholesterol, BMI, use of glucose-lowering agents, and income, this graded association of HbA1c with LEA was still present.


CONCLUSIONS
The current study conducted in a low-income population suggests a graded association between HbA1c and the risk of LEA among both African American and white patients with type 2 diabetes.
Corresponding author: Gang Hu, gang.hu@pbrc.edu.
Wenhui
W
Zhao
Peter T
PT
Katzmarzyk
Ronald
R
Horswell
Yujie
Y
Wang
Jolene
J
Johnson
Steven B
SB
Heymsfield
William T
WT
Cefalu
Donna H
DH
Ryan
Gang
G
Hu
D000328:Adult; D001741:Black or African American; D000671:Amputation, Surgical; D001786:Blood Glucose / Q000032:analysis*; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000150:complications*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D015994:Incidence; D035002:Lower Extremity / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011203:Poverty; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk; D012307:Risk Factors; D044465:White People
D001786:Blood Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human