[The metabolic memory phenomenon in predicting a risk for vascular complications in diabetes mellitus]

[A 20-year prospective follow-up study to evaluate the development of retinopathy and nephropathy after the onset of type 1 diabetes mellitus: Contribution of glycemic control and metabolic memory]

AIM

To assess the time course of changes in the level of glycated hemoglobin (HbA1c) for 20 years after the onset of type 1 diabetes mellitus (T1DM) and to compare its correlation with the development of microvascular complications, such as diabetic retinopathy (DR) and diabetic nephropathy (DN).

SUBJECTS AND METHODS

A total of 187 children with new-onset T1DM were registered in Moscow in 1994. During the 20-year follow-up study, these patients underwent regular check-ups at the Endocrinology Research Center, Ministry of Health of the Russian Federation, which included assessment of physical data, HbA1c 2-4 times a year, biochemical blood and albuminuria tests (once per year), and ophthalmologic examination (twice a year). A total of 155 people fully completed the 20-years follow-up study.

RESULTS

During the 20-year follow-up period after the onset of T1DM, 86 of the 155 patients developed microvascular complications: DR and DN in 86 (55.5%) and 24 (15.5%) cases, respectively; while DR concurrent with DN were noted in 20 patients. By the time of their last visit, 69 (44.5%) patients had no evidence suggesting the presence of microvascular complications. The level of HbA1c at the onset of the disease in patients who later developed the complications was higher than in those without complications (10.2±0.6 and 8.5±0.2%, respectively (p = 0.003). The statistically significant differences in HbA1c levels between the groups persisted during subsequent 15 years of follow-up, averaging 9.2±1.5, 9.7±0.9, and 8.1±0.7% after 5, 10, and 15 years, respectively, in the complication group and 7.1±0.3, 8.1±0.4, and 7.2±0.2% in the non-complication group (p < 0.01). Over the last 5 years of the follow-up, the mean HbA1c level between the groups was not significantly different, which at the end of the 20-year follow-up period was 7.8±0.3 and 7.4±0.6%, respectively (p > 0.05). The mean duration of T1DM, in which DR developed, was 9.6±6.2, 11.0±2.0, and 13.6±4.6 years for the non-proliferative, pre-proliferative, and proliferative stages, respectively. That of T1DM, in which DN developed, was 11.8±0.6 years for microalbuminuria and 16.1±1.3 years for macroalbuminuria.

CONCLUSION

The 20-year clinical follow-up of patients who had fallen ill with T1DM in childhood showed that diabetic microangiopathies developed with the long-term preservation of poor blood glucose control (BGC) starting at the onset of the disease. At the same time, the complications progressed to more severe stages, despite a clear trend toward better BGC. This may be suggestive of the negative metabolic memory phenomenon, which necessitates stable BGC, starting at the onset of the disease, for the prevention of microvascular complications.

The role of «metabolic memory» mechanisms in the development and progression of vascular complications of diabetes mellitus

The study of diabetes mellitus (DM), its complications and related pathologies has been continuously performed for many years; however, despite the substantial work and outstanding achievements in studying the mechanisms of DM development and the success of new medicinal products for controlling glycaemia, the problems associated with the late complications of DM continue to increase. The importance of glycaemic control in the early stages of DM for the development of complications is seen only after a sufficiently long period of observation. Such a delayed effect of primary good or unsatisfactory metabolic control, which shapes the patients clinical fate to a greater extent, is termed metabolic memory. The disorders developed under the influence of hyperglycaemia persist for long periods after the normalisation of carbohydrate metabolism; moreover, the effect of previous hyperglycaemia extends over the next 20 and even 30 years. Current research is focused on the possible mechanisms of metabolic memory development, including oxidative stress, advanced glycation end products and epigenetic mechanisms. This research will provide insight into potential markers for the early development and progression of vascular complications and new therapeutic possibilities for the future. However, determining the probable point of no return is more important, which implies that a point exists; after this point is crossed, the progression of vascular complications associated with DM cannot be prevented or reversed. The results of numerous experimental studies demonstrate that the prerequisite components of metabolic memory can be used as potential markers of the progression of DM complications, and may be potential therapeutic targets.

The values of cardio-ankle vascular and ankle-brachial indices in patients with carbohydrate metabolic disorders: The ESSE-RF study in the Kemerovo Region

Aim. To investigate factors associated with pathological cardio-ankle vascular and ankle-brachial indices (CAVI and ABI) in patients with carbohydrate metabolic disorders (CMD). Subjects and methods. A cross-sectional study was conducted in the framework of the multicenter epidemiological study “Epidemiology of Cardiovascular Diseases and Their Risk Factors in the Russian Federation” (ESSE-RF) in March to October 2013. The standard ESSE-RF protocol was extended by an additional study of peripheral arterial stiffness, by estimating CAVI and ABI automatically. A sample of 1619 people was formed in several stages, in which 311 patients with type 2 diabetes mellitus and prediabetes were identified and divided into 3 groups: 1) 41 patients with pathological CAVI values (≥9.0); 2) 241 with normal CAVI (