RETINOPATHY, BUT NOT NEUROPATHY, IS INFLUENCED BY THE LEVEL OF RESIDUAL ENDOGENOUS INSULIN-SECRETION IN TYPE-2 DIABETES

The files of 132 patients with Type 2 diabetes were retrospectively st udied To characterize the influence of metabolic control and residual insulin secretion on neuropathy and retinopathy, the two most frequent degenerative diabetic complications. Patients were classified accordi ng to their metabolic control (mean HbA(1c) either < or greater than o r equal to 8%; reference values: 3-6%) and residual endogenous insulin secretion (fasting plasma C-peptide levels either < or greater than o r equal to 0.600 nmol/l). Neuropathy was more frequent in patients wit h poor metabolic control (32/64 = 50%) than in those adequately contro lled (17/68 = 25%; p < 0.005). In both subgroups, the level of endogen ous insulin secretion did not influence the prevalence of neuropathy. Retinopathy was less effected than neuropathy by the degree of metabol ic control (37.5% in the subgroup with HbA(1c) greater than or equal t o 8% v.s. 25% in the subgroup with HbA(1c) < 8%; p < 0.10), but was in fluenced by residual insulin secretion. Indeed, in patients with inade quate metabolic control, the prevalence of retinopathy was significant ly increased in those with higher endogenous insulin secretion (51.4 v ersus 20.6%, p < 0.02) and thus probably higher insulin resistance. Fu rthermore, higher systolic arterial blood pressure was observed in the subgroups with a higher prevalence of retinopathy. Such conclusions w ere confirmed using multivariate analysis. Thus, in Type 2 diabetes, n europathy is essentially affected by the degree of metabolic control, whereas retinopathy is also influenced by the level of residual endoge nous insulin secretion and the presence of systolic hypertension.