Kidney function and size in diabetics before and during initial insulin treatment

Glomerular filtration rate (GFR), renal plasma flow (RPF) and kidney size are elevated in short-term insulin-dependent diabetics (IDD), [1–5]. A positive correlation between kidney size and GFR as well as RPF has been demonstrated [3–5]. Insulin treatment of newly diagnosed IDD patients for 3 months induces a reduction in kidney size and GFR [6]. Morphometric studies have demonstrated enlargement of glomeruli and increased glomerular filtration surface area in newly diagnosed and short-term IDD patients [7, 8]. Furthermore, a close correlation between glomerular filtration surface area and GFR has been demonstrated in IDD [8]. These observations have led to the suggestion that increased kidney size and glomerular filtration surface area are the major, even the sole, determinants of the elevated GFR in IDD [9]. Studies on the effect of improved metabolic control on GFR have, however, led to the suggestion that part of the increase in GFR is due to enhanced RPF and transglomerular filtration pressure [4, 10].Kidney size and function were measured before and during the initial week of insulin treatment in newly diagnosed young IDD patients to evaluate the validity of the above-mentioned concepts regarding the elevated GFR in IDD patients (morphological versus functional origin)