GLUCOSE-TOLERANCE DURING PROGRESSION OF CHRONIC-RENAL-FAILURE

Glucose tolerance (GT) and insulin (I) levels were examined after an o ral glucose (G) load (75g) in 45 patients with chronic renal failure ( CRF) (26 M, 19 F aged 60 +/- 10 years) divided into four groups accord ing to dietary regimen and serum creatinine (sCr). Three groups (CRF-I : sCr>1.5-less than or equal to 3 mg/dl; CRF-II: sCr>3-less than or eq ual to 6 mg/dl; CRF-III: sCr>6 mg/dl) followed a conventional low-prot ein diet (CD), and the fourth (CRF-IV: sCr>4.5 mg/dl) comprised patien ts on a vegetarian supplemented diet (SD). Before the test, patients w ere examined for PTH levels. The effects of progressive CRF, diet (CD vs SD) and PTH were investigated in comparison with a control group (n =12; 8 M, 4 F aged 47+/-8 years). G levels were significantly higher a t T90 and T120 in patients with advanced renal failure (CRF-III and CR F-IV) regardless of the diet. However, I levels were increased at T90 and T120 from early renal insufficiency and further increased with the progression of CRF. Despite the increase, I secretion was still inade quate to overcome the insulin-resistant state and maintain GT in patie nts with advanced renal failure (CRF-III and CRF-IV). PTH was signific antly increased in groups I-III. Despite the almost normal PTH concent ration and higher I levels than the CD group, SD patients still had im paired GT. Our results indicate that patients on SD do not have better GT than patients on CD and suggest secondary hyperparathyroidism as o nly one of the many contributory factors affecting insulin release and GT in uremia.