天美传媒

Time in range; Type 2 diabetes; Microvascular complications; Continuous glucose monitoring; Diabetic retinopathy; Diabetic nephropathy; Peripheral neuropathy; Glycemic variability; HbA1c; Longitudinal study

Introduction

Microvascular complications such as retinopathy, nephropathy, and neuropathy are among the most serious consequences of poorly managed Type 2 diabetes. Historically, HbA1c has served as the gold standard marker for assessing long-term glycemic control and predicting the risk of complications. However, HbA1c represents an average and does not reflect daily glucose fluctuations or acute excursions, which may contribute to microvascular damage [1-5]. With the rise of continuous glucose monitoring (CGM), a more dynamic and granular metric—Time in Range (TIR), defined as the percentage of time glucose levels stay between 70–180 mg/dL—has emerged as a complementary and potentially superior indicator of glucose control. This prospective cohort study investigates the association between TIR and the risk of developing microvascular complications in adults with Type 2 diabetes over a period of five years [6-10].

Discussion

A total of 800 adults with Type 2 diabetes, aged 40–75 years and free from advanced microvascular complications at baseline, were enrolled in the study. Participants were monitored using CGM devices every 3–6 months, and their TIR was calculated and averaged over time. In addition to standard clinical assessments such as HbA1c, eGFR, urinary albumin-to-creatinine ratio, retinal imaging, and monofilament testing were conducted annually to assess the onset or progression of diabetic nephropathy, retinopathy, and peripheral neuropathy.

The findings revealed a clear inverse relationship between TIR and the incidence of microvascular complications. Patients with a TIR greater than 70% had significantly lower rates of nephropathy (9% vs. 22%), retinopathy (6% vs. 18%), and neuropathy (11% vs. 25%) compared to those with TIR below 50%, even after adjusting for HbA1c, age, disease duration, and other covariates. While HbA1c remained a relevant predictor, it was less strongly associated with outcomes than TIR. Notably, patients with higher glycemic variability (despite similar HbA1c levels) had a greater risk of complications, suggesting that maintaining stable glucose levels within range may be more protective than simply achieving a low average.

Subgroup analysis showed that the predictive value of TIR was consistent across different treatment regimens, including insulin, oral medications, and lifestyle management. Patients using real-time CGM with alert features were more likely to achieve and maintain higher TIR, highlighting the importance of access to advanced monitoring tools in chronic disease management. Despite the study’s strengths—including its prospective design, large sample size, and comprehensive assessments—limitations included reliance on intermittent CGM use (not continuous throughout the year) and a single geographic region, which may affect generalizability.

Conclusion

This study provides compelling evidence that Time in Range (TIR) is a strong and independent predictor of microvascular complications in adults with Type 2 diabetes. Patients who maintained TIR above 70% had significantly lower risks of developing nephropathy, retinopathy, and neuropathy over five years, regardless of their HbA1c values. These findings support the incorporation of TIR into routine clinical practice as a key metric for glycemic assessment and therapeutic goal-setting. Moreover, they emphasize the need for broader access to CGM technologies to empower patients with real-time data for proactive diabetes management. Future research should aim to standardize TIR-based targets in clinical guidelines and further explore its predictive value in macrovascular outcomes and overall mortality.

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