The frequency and severity of retinopathy are related to HbA1c values after, but not at, the diagnosis of NIDDM

OBJECTIVES: To examine the relationship between previous glycaemic exposure and prevalence of retinopathy 8 years after diagnosis of diabetes in 58 islet cell antibodies (ICA)-negative noninsulin-dependent diabetes mellitus (NIDDM) patients and in a group of 14 ICA-positive 'NIDDM' and insulin-dependent diabetes mellitus (IDDM) patients. DESIGN AND METHODS: The Wisconsin retinopathy scale was used to assess the retinopathy which was graded into mild, moderate and severe nonproliferative diabetic retinopathy (NPDR), or proliferative retinopathy (PDR). The frequency and severity of retinopathy was related to HbA1c levels at diagnosis, and 3 and 5 years later. RESULTS: Thirty of the 58 ICA-negative NIDDM patients (52%) but only 2 of the 14 ICA-positive 'NIDDM' or IDDM patients (14%) had mild-moderate-severe NPDR 8 years after diagnosis (P = 0.02). None had PDR. Retinopathy 8 years after diagnosis in NIDDM (= 58 ICA-negative patients) was correlated with the degree of glycaemic control (HbA1c levels) at 3 and 5 years after diagnosis, but not to HbA1c levels at diagnosis. The relative risk for a higher average HbA1c (per percentage) at 3 and 5 years was 1.56 for any retinopathy vs. no retinopathy (95% confidence interval 1.1-2.2; P = 0.01) and 1.68 for moderate to severe NPDR in comparison with no DR and mild NPDR (95% confidence interval 1.0-2.8; P = 0.04). CONCLUSIONS: Retinopathy after 8 years of diabetes in NIDDM patients was associated with impaired glycaemic control during previous years but not with glycaemic control at baseline. Good glycaemic control may prevent retinopathy in patients with NIDDM.