Intensified conventional insulin treatment retards the microvascular complications of insulin‐dependent diabetes mellitus (IDDM): the Stockholm Diabetes Intervention Study (SDIS) after 5 years

Abstract. Ninety‐six patients with insulin‐dependent diabetes mellitus (IDDM) and non‐proliferative retinopathy were randomized to intensified conventional treatment (ICT) (n = 44) or regular treatment (RT) (n = 52), and followed up for 5 years. HbA1c decreased from 9.5 ± 0.2% (mean value ± SEM) to 7.2 ± 0.1% in the ICT group, and from 9.4 ± 0.2% to 8.7 ± 0.1% in the RT group (difference between the groups, P < 0.001). Retinopathy increased in both groups (P < 0.001), but after 5 years it was worse in the RT group (P < 0.05). The urinary albumin excretion rate was higher in the RT group than in the ICT group after 5 years (239.9 ± 129.7 μg min−1 vs. 46.0 ± 26.1 μg min−1, P < 0.05). Eight RT patients developed manifest nephropathy, compared with none in the ICT group (P < 0.01). After 5 years the conduction velocities of the sural (P < 0.05), peroneal (P < 0.01) and tibial (P < 0.001) nerves were lower in the RT group. The respiratory sinus arrhythmia was 12.1 ± 1.2 beats min−1 in the RT group and 16.7 ± 1.4 beats min−1 in the ICT group at the end of the study (P < 0.01). The increases in retinopathy (P < 0.01), nephropathy (P < 0.01) and neuropathy (P < 0.001) were all related to the mean HbA1c value during the study. Smoking habits only influenced the progression of retinopathy (P < 0.05). Serious hypoglycaemia occurred in 34 ICT patients and 29 RT patients (242 and 98 episodes, respectively) (P < 0.05). Whereas weight was stable in the RT group, the body mass index increased by 5.8% in the ICT group (P < 0.01). In conclusion, microvascular complications of diabetes were retarded by intensified conventional insulin treatment. However, such treatment increased the frequency of serious hypoglycaemia, and led to an increase in body weight.