title: Vitamin D levels, microvascular complications, and mortality in type 1 diabetes.
abstract: OBJECTIVE
  To evaluate vitamin D as a predictor of all-cause mortality, progression from normoalbuminuria to micro- or macroalbuminuria, and the development of background or proliferative retinopathy in patients with type 1 diabetes.
  
  
  METHODS
  A prospective observational follow-up study in which an inception cohort of type 1 diabetic patients was followed from onset of diabetes diagnosed between 1979 and 1984. Plasma vitamin D [25(OH)D3] levels were determined by high performance liquid chromatography/tandem mass spectrometry in 227 patients before the patients developed microalbuminuria. Values equal to or below the 10% percentile (15.5 nmol/L) were considered severe vitamin D deficiency.
  
  
  RESULTS
  Median (range) vitamin D was 44.6 (1.7-161.7) nmol/L. Vitamin D level was not associated with age, sex, urinary albumin excretion rate (UAER), or blood pressure. During follow-up, 44 (18%) patients died. In a Cox proportional hazards model, the hazard ratio for mortality in subjects with severe vitamin D deficiency was 2.7 (1.1-6.7), P = 0.03, after adjustment for UAER, HbA(1c), and conventional cardiovascular risk factors (age, sex, blood pressure, cholesterol, smoking). Of the 220 patients, 81 (37%) developed microalbuminuria and 27 (12%) of these progressed to macroalbuminuria. Furthermore, 192 (87%) patients developed background retinopathy, whereas 34 (15%) progressed to proliferative retinopathy. Severe vitamin D deficiency at baseline did not predict the development of these microvascular complications.
  
  
  CONCLUSIONS
  In patients with type 1 diabetes, severe vitamin D deficiency independently predicts all-cause mortality but not development of microvascular complications in the eye and kidney. Whether vitamin D substitution in type 1 diabetic patients can improve the prognosis remains to be investigated.
authors.affiliation: Steno Diabetes Center, Gentofte, Denmark. cijq@steno.dk
authors.forename: Christel
authors.initials: C
authors.lastname: Joergensen
authors.forename: Peter
authors.initials: P
authors.lastname: Hovind
authors.forename: Anne
authors.initials: A
authors.lastname: Schmedes
authors.forename: Hans-Henrik
authors.initials: HH
authors.lastname: Parving
authors.forename: Peter
authors.initials: P
authors.lastname: Rossing
mesh_terms: D000293:Adolescent; D000328:Adult; D000419:Albuminuria / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000401:mortality*; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D053719:Tandem Mass Spectrometry; D014807:Vitamin D / Q000097:blood*; D055815:Young Adult
chemical_list: D014807:Vitamin D