title: Calculated Daily Insulin Dosages Overestimate Prescribed Insulin Doses in Type 2 Diabetes: A Primary Care Database Study.
abstract: The aim was to compare the prescribed and calculated daily insulin dosages based on prescription data in type 2 diabetes patients in a general practice database.
  
  
  
  A total of 17 782 type 2 diabetes patients (age: 70.0 ± 11.5 years; 52% males; 16% diabetologist care) with ≥2 insulin prescriptions from 834 practices were analyzed (Disease Analyser: 01/2011-12/2015). Prescribed daily dosage (PDD) (physician documentation) and calculated daily dose (CDD) (pack size × strength × volume / days between 2 prescriptions) were calculated for short-acting, long-acting, and premixed insulins. PDD and CDD were compared using paired t-tests. Linear regression models assessed the associations of insulin dosage difference (CDD-PDD) with age, sex, diabetologist care, private health insurance, obesity, HbA1c, hypertension, hyperlipidemia, macro- and microvascular complications.
  
  
  
  Mean [SD] CDDs were higher than PDDs for short-acting (52 [28] vs 48 [26] units/day), long-acting (30 [20] vs 24 [15] units/day), and premixed (46 [26] vs 40 [21] units/day) insulins (all P < .05). In regression models, age (per year) was associated with higher CDD-PDD differences (+0.11, +0.04, +0.10; P < .01) for short-, long-acting, and premixed insulins, respectively. Diabetologist care was related to lower differences (-2.92, -1.02, -3.65; all P < .05). HbA1c was associated with higher differences in long-acting and premixed insulins, but was related to a lower difference in short-acting insulins (all P < .05).
  
  
  
  CDD in primary care database studies substantially overestimate the PDD (8-25%). Age, diabetologist care, and glycemic control were related to CDD-PDD differences. Priming and safety shots with pens, dosing errors, or the accumulation of insulin reserves by patients may be underlying reasons.
authors.affiliation: 1 Epidemiology, IMS Health, Frankfurt am Main, Germany.
authors.forename: Karel
authors.initials: K
authors.lastname: Kostev
authors.affiliation: 2 German Diabetes Center, Institute for Biometrics and Epidemiology, Düsseldorf, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rathmann
mesh_terms: D000328:Adult; D000368:Aged; D016208:Databases, Factual; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy*; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007328:Insulin / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D011320:Primary Health Care
chemical_list: D007004:Hypoglycemic Agents; D007328:Insulin
keywords: adherence; daily dose; diabetes; insulin; primary care