title: Elevation of fasting morning glucose relative to hemoglobin A1c in normoglycemic patients treated with niacin and with statins.
abstract: BACKGROUND
  Niacin increases fasting glucose levels, and statins modestly increase the rate of new-onset diabetes. The clinical importance and mechanisms of these effects are not fully explored.
  
  
  OBJECTIVE
  On the basis of anecdotal observations, we hypothesized that elevated morning fasting glucose may be accompanied by relatively normal hemoglobin A1c (HbA1c) in patients treated with niacin and other lipid-modifying drugs. We conducted a retrospective cohort analysis to test this hypothesis.
  
  
  METHODS
  The Duke Lipid Clinic database (1994-2007) was screened for simultaneous determinations of fasting morning glucose and HbA1c, yielding 1483 data pairs among 554 subjects. Subjects with diabetes, by clinical diagnosis, medication, or any HbA1c ≥6.5%, or nondiabetes were analyzed separately. Repeated-measures linear regression featured glucose as dependent variable and included terms for HbA1c, drug(s), and their interaction.
  
  
  RESULTS
  Regression lines for glucose on HbA1c had altered slopes in the presence of niacin and/or statin use in normoglycemic subjects. The corresponding interaction terms (drug and HbA1c) were significant (niacin P = .026, statin P = .013). Fibrate use had no effect (interaction P = .49). When modeled together, niacin and statin effects were independent. Regression curves in diabetic patients were not affected by lipid medications.
  
  
  CONCLUSIONS
  Elevated fasting glucose may be accompanied by relatively normal HbA1c in niacin- and statin-treated patients. HbA1c reflects average daily glucose levels and is likely a better measure of the glycemic effect of lipid medications. Because our data were retrospective, confirmation from randomized trials is needed.
authors.affiliation: Beaumont Hospital, Royal Oak, MI, USA.
authors.forename: Veena
authors.initials: V
authors.lastname: Rajanna
authors.forename: Kristen B
authors.initials: KB
authors.lastname: Campbell
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Leimberger
authors.forename: Bibhu D
authors.initials: BD
authors.lastname: Mohanty
authors.forename: John R
authors.initials: JR
authors.lastname: Guyton
mesh_terms: D001786:Blood Glucose / Q000378:metabolism*; D015331:Cohort Studies; D016208:Databases, Factual; D003920:Diabetes Mellitus / Q000097:blood / Q000188:drug therapy / Q000503:physiopathology; D005215:Fasting / Q000097:blood*; D005260:Female; D058607:Fibric Acids / Q000627:therapeutic use; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009525:Niacin / Q000627:therapeutic use*; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D058607:Fibric Acids; D006442:Glycated Hemoglobin; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D009525:Niacin; C517652:hemoglobin A1c protein, human