The study shows that the positive effects of tight blood glucose control can be seen many years later. At the end of the study period, patients who had controlled their blood sugar tightly ever since the start of the study were 51% less likely to have nerve problems than patients who started the study at the same time but did not have the initial five-year period of intensive blood sugar control.
The study, published in the journal Diabetes Care, involved 1,441 people with type 1 diabetes and began in the 1980s. Participants were randomly assigned to either tight blood-sugar control using three insulin injections per day or an insulin pump, or to more typical blood sugar control for the time, using one to two insulin injections a day. The latter group was later encouraged to adopt tight blood sugar control, and the study tracked all patients’ health.
The symptoms and signs of foot pain were then assessed using a standardized questionnaire and physical examinations. After the first year, 28% of the regular-control patients showed signs of neuropathy on their physical exam, though only 4.7% reported symptoms on their questionnaires. By contrast, 17.8% of the tight-control patients had neuropathy signs on their foot exams, and 1.8% reported symptoms. The difference between the two groups was highly statistically significant.
Over time, the difference between the two groups continued to be significant, although the percentage of both groups that showed signs or reported symptoms of neuropathy increased over time. By the end of the eighth year of follow-up, almost 7% of the participants who had been in the regular-control group reported feeling symptoms of neuropathy, compared with about 3.5% of the tight-control patients. And more than 26% of regular-control participants had signs of neuropathy on their physical exam, compared with just over 20% of tight-control participants.