LETTER
Microalbuminuria, Lipoproteins, and Diabetic Control
Andrew G. Bostom and
Peter W. F. Wilson
15 February 1993 | Volume 118 Issue 4 | Pages 312-313
TO THE EDITOR:
In their cross-sectional analysis, Ramirez and colleagues [1] provide no data regarding microalbuminuria, nor did the preliminary studies cited by Ramirez and colleagues show either a cross-sectional (their references 30 and 32), or short-term longitudinal (their reference 31) relation between lipoprotein (a) (Lp[a]) level and glycemic control. Categorizing either insulin- or non-insulin-dependent diabetics by the presence or absence of the nephrotic syndrome is insufficient when assessing their Lp(a) levels and the possibly related risk for accelerated atherosclerotic disease.
Karadi and colleagues [2], the first to report significantly increased Lp(a) concentrations in association with nephrosis, found no correlation between daily protein loss or selectivity index and Lp(a) concentration. Jenkins and colleagues [3] reported that apolipoprotein (a) (apo [a]) levels in insulin-dependent diabetics (n = 107) were elevated in those with microalbuminuria and did not correlate with glycemic control. Patients with microalbuminuria had significantly higher apo (a) levels (geometric mean, 245 U/L compared with 196 U/L; P < 0.005), despite glycosylated hemoglobin (HbA1c) concentrations that were significantly lower than those in the albuminuric patients (mean, 8.8% compared with 9.8%; P < 0.05).
Microalbuminuria is predictive of increased mortality in non-insulin-dependent diabetes [4]. Data from the original population-based Framingham cohort suggest that trace proteinuria determined by dipstick is associated with significantly increased overall and cardiovascular disease-related mortality [5]. The interrelation of quantitative microalbuminuria, Lp(a), HbA1c, and cardiovascular disease should be examined prospectively in a population that includes persons with normal glucose tolerance, documented glucose intolerance, and overt diabetes mellitus.
1. Ramirez LC, Arauz-Pacheco C, Lackner C, Albright G, Adams BV, Raskin P. Lipoprotein (a) levels in diabetes mellitus: relationship to metabolic control. Ann Intern Med. 1992; 117:42-7.
2. Karadi I, Romics L, Palos G, Doman J, Kaszas I, Hesz A, et al. Lp(a) lipoprotein concentration in serum of patients with heavy proteinuria of different origin. Clin Chem. 1989; 35:2121-3.
3. Jenkins AJ, Steele JS, Janus ED, Best JD. Increased plasma apolipoprotein (a) levels in IDDM patients with microalbuminuria. Diabetes. 1991; 40:787-90.
4. Mogensen CE. Microalbuminuria predicts clinical proteinuria and early mortality in maturity-onset diabetes. N Engl J Med. 1984; 310: 356-60.
5. Kannel WB, Stampfer MJ, Castelli WP, Verter J. The prognostic significance of proteinuria: the Framingham Study. Am Heart J. 1984; 108:1347-52.
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