Background and purpose: Diabetic nephropathy is an important complication of diabetes types 1 and 2 and contributes to overall morbidity and mortality. Incidence and prevalence data often come from controlled clinical studies and there is only few information obtained on the primary care level. TUV is an abbreviation for "Technischer Uberwachungsverein" (Technical Safety Standards Authority) which regularly checks cars and technical equipment in Germany. In analogy to this, the name "diabetes TUV" was chosen to demonstrate the continuous surveillance of diabetic patients. The diabetes TUV is an initiative of the "Deutsche Betriebskrankenkasse" ("Deutsche BKK"), with 1.1 million members the largest works sickness fund in Germany, that have entered into a contract with the German associations of family physicians and ophthalmologists to improve integrated care for patients with diabetes. The aim of this retrospective study was to screen the diabetes TUV registry data regarding nephropathy.
Patients and methods: A total of 4,893 patients insured with the Deutsche BKK being treated in 351 different medical practices were screened for diabetes-related complication in the state of Lower Saxony from July 26, 2000 to July 10, 2004. Only the first documentation sheets (n = 4,869) were used for analysis of albuminuria and serum creatinine values. The calculated clearance (modification of diet in renal disease [MDRD] formula) was used for classification of renal insufficiency according to the Kidney Disease Outcomes Quality Initiative (K/DOQI) stages.
Results: Pathologic values of albuminuria (> 20 mg/l or "positive") were found in the survey sheets of 18% of all patients. Further analysis of the data revealed, however, a strong clustering of values suggesting problems with the documentation process. Elevated serum creatinine was found in 4.7% of patients. There was a strong correlation of the MDRD-calculated clearance values with those obtained with the Cockcroft-Gault formula. 89% of all diabetic patients (77% type 1 and 90% type 2) had an MDRD formula-calculated clearance < or = 89 ml/min/1.73 m(2) corresponding to K/DOQI stages 2-5. Compared with type 1, more patients with type 2 diabetes were in the K/DOQI stages 2 and 3. 2.2% of all type 1 and 0.5% of all type 2 diabetics exhibited K/DOQI stage 5 (GFR < 15 ml/min/1.73 m(2) or dialysis-dependent renal insufficiency).
Conclusion: The analysis of the diabetes TUV data has revealed a higher prevalence of renal disease as previously described. Data clustering could be an indicator of documentation failure. From the obtained information, it cannot be determined whether the decrease in renal function in the diabetes TUV patients is due to diabetic nephropathy and/or other renal diseases. The diabetes TUV of the Deutsche BKK is a valuable approach to detect early renal abnormalities in diabetic patients on the primary care level. The quality of documentation, however, must be improved.