Objective: To explore the nature of diabetic complications in type 2 diabetic patients who had had diabetes for longer than 15 years (long-DM), compared to those with duration of less than 15 years (short-DM).
Material and Method: Patients studied were adult type 2 diabetic patients registered to the Diabetes Registry Project, a nationwide cross-sectional study of diabetes mellitus in Thailand. Information collected included demographic data, age at diagnosis of diabetes, blood pressure, body mass index, fasting plasma glucose, HbA1c, serum creatinine, and major diabetic vascular complications, including diabetic retinopathy (DR), albuminuria or renal insufficiency (diabetic nephropathy; DN), myocardial infarction (MI), stroke, peripheral arterial disease (PAD), foot ulcer and amputation.
Results: There were 9284 patients, consisting of 2244 (24.17%) subjects with long-DM (mean + SD, mean duration of DM 21.3 + 5.8 years), and 7040 subjects with short-DM (mean duration 7.0 + 3.9 years). The long-DM group was older than the short-DM group (65.5 + 10.3 vs 58.2 + 12.6 year old, p less than 0.0001), and had higher HbA1c (8.5 vs 8.0%, p = 0.009). The prevalence of diabetic complications in the long-DM group was higher than that in the short-DM group (DN 49.4% vs 33.9%, DR 54.3% vs 22.8%; MI 9.4% vs 3.5%, PAD 17.3% vs 5.5%, foot ulcer 13.4% vs 5.3%,, stroke 9.4% vs 7.0% and amputation 5.5% vs 2.0%; all p values less than 0.01). The duration of DM significantly affected the risk of diabetic complications after adjustment for age, hypertension, and levels of glycemic control.
Conclusion: Diabetic duration was independently associated with increased risk of having diabetes-related complications without threshold. Monitoring of complications in patients having long-standing diabetes is warranted in order to provide appropriate management.

Keywords: Vascular complications, Long-standing diabetes