Metabolic control and complications over 3 years in patients with insulin dependent diabetes (IDDM): the Stockholm Diabetes Intervention Study (SDIS)

In a planned 5-year study, 97 patients with insulin dependent diabetes mellitus (IDDM), non-proliferative retinopathy and unsatisfactory blood glucose control were monitored for 3 years. The patients were randomized to an intensified conventional treatment (ICT, n = 44) or a regular treatment (RT, n = 53) group. HbA1c (normal range 3.9-5.7%) was reduced from 9.5 +/- 0.2 (mean value +/- SEM) to 7.4 +/- 0.1% in the ICT group (P = 0.0001), and from 9.5 +/- 0.2 to 9.0 +/- 0.2% in the RT group (P = 0.004). Nerve conduction velocities in the sural and peroneal nerves (P = 0.01-0.0001) were impaired in the RT group, but not in the ICT group. Retinopathy increased in both groups. The condition of 22 ICT patients (50%, 95% confidence interval 34-66%) and 37 RT patients (73%, 61-84%) deteriorated with regard to at least one microvascular complication (retinopathy, nephropathy, neuropathy) (P = 0.024). Lower HbA1c levels during the study significantly reduced the risk of deterioration (P = 0.01). In total, 57% of the ICT patients had at least one episode of serious hypoglycaemia, compared with 23% in the RT group (P = 0.001). The patients in the ICT group also gained weight (P = 0.0001). Improved blood glucose control slowed down the progression of microangiopathy during a 3-year period in patients with non-proliferative retinopathy, but at the price of an increased frequency of serious hypoglycaemic episodes, and some gain in body weight.