title: Glycemic control and fracture risk in elderly patients with diabetes.
abstract: OBJECTIVE
  Elderly patients with diabetes are at increased fracture risk. Although long exposure to hyperglycemia may increase fracture risk via adverse effects on bone metabolism, tight glycemic control may increase risk via trauma subsequent to hypoglycemia. We tested the prospective relationship between glycemic control and fracture risk in 10,572 elderly patients (age ≥65) with diabetes.
  
  
  METHODS
  Geriatric patients with diabetes were drawn from Vanderbilt University Medical Center's Electronic Health Record. Baseline was defined as age at first HbA1c after the latter of age 65 or ICD 9 code for diabetes. Cox analysis was used to test the relationship of updated mean HbA1c (average HbA1c over follow-up) with time to first fracture since baseline. HbA1c was categorized as follows: <6.5% [<48mmol/mol]; 6.5-6.9% [48-52mmol/mol]; 7-7.9% [53-63mmol/mol]; 8-8.9% [64-74 mmol-mol]; ≥9% [≥75mmol/mol]. The number of BMI measurements was used as a surrogate for relative frequency of outpatient visits, i.e. patient-provider contacts.
  
  
  RESULTS
  During follow-up, there were 949 fracture events. HbA1c demonstrated a cubic relationship with fracture risk (p<0.05). In analyses accounting for age, sex, race, and number of BMI measures (a surrogate for patient-provider interaction), compared to an HbA1c of 7-7.9%, HRs (95% CIs) were: HbA1c<6.5% HR=0.97 (0.82-1.14), 6.5-6.9% HR=0.80 (0.66-0.97), 8-8.9% HR=1.13 (0.92-1.40), ≥9% HR=1.19 (0.93-1.54).
  
  
  CONCLUSIONS
  An HbA1c of 6.5-6.9% is associated with the lowest risk of fracture in elderly patients with diabetes. Risk associated with an HbA1c ≥9% may be a marker of infrequent patient-provider interaction.
authors.affiliation: Department of Epidemiology, West Virginia University, Morgantown, West Virginia P.O. Box 9127, Morgantown, WV 26505, United States. Electronic address: bnconway@hsc.wvu.edu.
authors.forename: Baqiyyah N
authors.initials: BN
authors.lastname: Conway
authors.affiliation: Department of Biostatistics, West Virginia University, Morgantown, West Virginia P.O. Box 9127, Morgantown, WV 26505, United States. Electronic address: dmlong@hsc.wvu.edu.
authors.forename: Dustin M
authors.initials: DM
authors.lastname: Long
authors.affiliation: Genesis Health Group Endocrinology, Bettendorf, Iowa 2535 Maplecrest Rd, Suite 10, Bettendorf, IA 52722, United States. Electronic address: kathleen.figaro@gmail.com.
authors.forename: M Kathleen
authors.initials: MK
authors.lastname: Figaro
authors.affiliation: Department of Medicine, Vanderbilt University, Nashville, Tennessee 1215 21st Ave S #8210, Nashville, TN 37212, United States. Electronic address: Michael.E.May@Vanderbilt.Edu.
authors.forename: Michael E
authors.initials: ME
authors.lastname: May
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001786:Blood Glucose; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000188:drug therapy* / Q000453:epidemiology; D005260:Female; D050723:Fractures, Bone / Q000453:epidemiology* / Q000517:prevention & control; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D053208:Kaplan-Meier Estimate; D008297:Male; D011446:Prospective Studies; D012306:Risk
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; C517652:hemoglobin A1c protein, human
keywords: Diabetes; Fracture; Geriatric; Glycemic control; HbA1c; Hypoglycemia