Abstract: This review identified 17 randomized studies that addressed whether enhanced glucose control prevents the development of neuropathy. Seven of these studies were conducted in people with type 1 diabetes, eight in type 2 diabetes, and two in both types. A meta-analysis of the two studies that reported the primary outcome (incidence of clinical neuropathy) with a total of 1228 participants with type 1 diabetes revealed a significantly reduced risk of developing clinical neuropathy in those with enhanced glucose control, an annualized RD of -1.84% (95% confidence interval (CI) -1.11 to -2.56). In a similar analysis of four studies that reported the primary outcome, involving 6669 participants with type 2 diabetes, the annualized RD of developing clinical neuropathy was -0.58% (95% CI 0.01 to -1.17). Most secondary outcomes were significantly in favor of intensive treatment in both populations. However, both types of diabetic participants also had a significant increase in severe adverse events including hypoglycemic events. According to high-quality evidence, enhanced glucose control significantly prevents the development of clinical neuropathy and reduces nerve conduction and vibration threshold abnormalities in type 1 diabetes mellitus. In type 2 diabetes mellitus, enhanced glucose control reduces the incidence of clinical neuropathy, although this was not formally statistically significant (P = 0.06). However, enhanced glucose control does significantly reduce nerve conduction and vibration threshold abnormalities. Importantly, enhanced glucose control significantly increases the risk of severe hypoglycemic episodes, which needs to be taken into account when evaluating its risk/benefit ratio.

Plain-language summary: This review identified 17 randomized studies that addressed whether more aggressive attempts to lower blood glucose levels prevent people from developing neuropathy. Seven of these studies were conducted in people with type 1 diabetes, eight in type 2 diabetes, and two in both types. However, only two studies in type 1 diabetes including 1228 participants and four studies in type 2 diabetes including 6669 participants investigated our primary outcome. In type 1 diabetes, there was a significant effect of more aggressive therapies in preventing neuropathy compared with standard treatment. In type 2 diabetes, more aggressive therapy was also beneficial in preventing symptoms and signs of clinical neuropathy, but the result was not statistically significant as measured by the primary method selected for this review. However, there was a significant positive effect on the amount of nerve damage measured with electrical nerve conduction tests and a special machine to measure the threshold of detection of vibration in both types of diabetes. Overall, the evidence indicates that more aggressive treatments of sugar levels delay the onset of neuropathy in both types of diabetes. No other treatments have proven effective to date. However, the beneficial effect has to be balanced against the significantly increased risk of dangerously low blood sugar levels that can occur in both types of diabetes and which can lead to brain injury amongst other issues.