Tabaei et al. (1) conclude that “Microalbuminuria may not be as sensitive and specific a predictor of diabetic nephropathy as previously suggested. Other markers of risk for diabetic nephropathy are needed for optimal clinical management.”
This conclusion is based on a 7-year follow-up study of nine (eight women) normotensive type 1 diabetic patients with microalbuminuria and seven middle-aged normotensive type 2 diabetic patients (mainly women) with microalbuminuria. Their conclusions and proposals should be interpreted with great caution because numerous flaws are at hand: 1) a subset of only 32% of the original cohort was investigated, giving rise to many different kinds of biases as demonstrated, e.g., in relation to the included patient population; 2) the generally accepted criteria for microalbuminuria was not fulfilled, neither at baseline nor at the end of the study; 3) values for urinary albumin excretion rate or albumin/creatinine ratio were not presented; 4) the results dealing with progression are presented without any confidence interval, and because the number of patients was extremely small, the confidence interval would be extremely wide; 5) six of seven type 2 diabetic patients and two of nine type 1 diabetic patients received ACE inhibitors at the end of the follow-up; 6) no information of relevant treatment during the follow-up was presented; and 7) the authors have selected references that suit their purpose, including a review article (2) that disregarded all studies in microalbuminuric type 1 and type 2 diabetic patients lasting <5 years.
To compensate for this lack of a balanced view, we have included Table 1, which deals with the outcome of microalbuminuria in type 1 and type 2 diabetic patients. It is quite apparent from the table that the study by Tabaei et al. (1) is the smallest ever reported in the literature.
In conclusion, microalbuminuria is the best documented predictor of high risk for development of diabetic nephropathy in both type 1 and type 2 diabetes, and numerous trials in type 1 (3–9) and type 2 (12–17) diabetes have documented and demonstrated the usefulness of microalbuminuria in intervention studies.
Progression of microalbuminuria to nephropathy in diabetic patients
| Author (reference) . | n . | Observation period (years) . | Patients developing nephropathy (%/years) . |
|---|---|---|---|
| Type 1* | |||
| Viberti et al. (3) | 46 | 2 | 13 |
| Laffel et al. (4) | 70 | 2 | 9.3 |
| Crepaldi et al. (5) | 34 | 3 | 6.9 |
| Euclid Study Group (6) | 34 | 2 | 10.2 |
| Mathiesen et al. (7) | 23 | 4 | 7.5 |
| Prima Study Group (8) | 18 | 2 | 0 |
| Atlantis Study Group (9) | 46 | 2 | 5.5 |
| Type 2 | |||
| Mogensen et al. (10) | 59 | 9 | 2.4 |
| Nelson et al. (11) | 50 | 4 | 9.3 |
| Ravid et al. (12) | 49 | 5 | 8.4 |
| Gaede et al. (12) | 80 | 4 | 5.8 |
| Ahmad et al. (14) | 51 | 5 | 4.8 |
| Estacio et al. (15) | 150 | 5 | 4.0 |
| HOPE Study Group (16) | 1140 | 4.5 | 4.5 |
| Parving et al. (17) | 201 | 2 | 7.5 |
| Parving et al. (18) | 86 | 5 | 7.0 |
| Author (reference) . | n . | Observation period (years) . | Patients developing nephropathy (%/years) . |
|---|---|---|---|
| Type 1* | |||
| Viberti et al. (3) | 46 | 2 | 13 |
| Laffel et al. (4) | 70 | 2 | 9.3 |
| Crepaldi et al. (5) | 34 | 3 | 6.9 |
| Euclid Study Group (6) | 34 | 2 | 10.2 |
| Mathiesen et al. (7) | 23 | 4 | 7.5 |
| Prima Study Group (8) | 18 | 2 | 0 |
| Atlantis Study Group (9) | 46 | 2 | 5.5 |
| Type 2 | |||
| Mogensen et al. (10) | 59 | 9 | 2.4 |
| Nelson et al. (11) | 50 | 4 | 9.3 |
| Ravid et al. (12) | 49 | 5 | 8.4 |
| Gaede et al. (12) | 80 | 4 | 5.8 |
| Ahmad et al. (14) | 51 | 5 | 4.8 |
| Estacio et al. (15) | 150 | 5 | 4.0 |
| HOPE Study Group (16) | 1140 | 4.5 | 4.5 |
| Parving et al. (17) | 201 | 2 | 7.5 |
| Parving et al. (18) | 86 | 5 | 7.0 |
Data based on the placebo arm in randomized double-blind studies lasting ≥2 years.
References
Address correspondence to Professor Hans-Henrik Parving, Steno Diabetes Center, Niels Steensensvej 2, DK-2820 Gentofte, Denmark. E-mail: hhp@novonordisk.com.
