It has been known for so long that optimal glycemic control in type 1 diabetes can decrease the risk of micro and macrovascular complications, but why is the risk still high despite intensive glycemic control?
It is known that type 1 diabetes is correlated with microvascular (retinopathy leading to blindness, nephropathy a major cause of kidney disease, and neuropathy a major cause of non-traumatic amputations) and macrovascular complications, with risks 10 times those of people without diabetes (including ischemic heart disease, cerebrovascular accident and peripheral vascular disease). There is vast evidence that hyperglycemia is strongly associated with micro and macrovascular complications of type 1 diabetes and optimal glycemic control decreases the risk of microvascular and macrovascular complications. However, despite intensive glycemic control in practice, the risk of complications still remains high. This suggests other factors and components of metabolic health, particularly in the context of routine clinical practice, may have a role in the significant risk of complications. For example, dyslipidemia leads to worse cardiovascular outcomes and neuropathy in type 1 diabetes, and hypertension has been linked to increased risk of mortality and end-stage complications. A cross-sectional study aimed to evaluate the associations between glycemia, adiposity, blood pressure and lipid risk factors and prevalent micro and macrovascular disease in people with type 1 diabetes.
This cross-sectional analysis was conducted on 920 patients with type 1 diabetes and based on clinic records information of their risk factors for micro and macrovascular diseases, and only those with complete data for risk factors (blood pressure, adiposity, triglycerides, HDL-c and LDL-c) were included. Cut-offs were set for risk factors, above which would be considered to have a risk factor abnormality. This cut-off criteria included BMI ≥30kg/m2, systolic blood pressure ≥130 mmHg and/or diastolic blood pressure ≥85 mmHg or use of blood pressure lowering medications, triglycerides ≥1.7mmol/L (30.6 mg/dL) or use of fibrates, HDL-c << 1.03 mmol/L (18.6 mg/dL).
Of those 920 participants enrolled with type 1 diabetes, 39% had retinopathy, 17% had nephropathy, and 10% neuropathy. 43% of participants with nephropathy had albuminuria, 13% had a renal transplant, 5% were on hemodialysis and the rest had intermediate disease. 11% of the participants enrolled had one or more macrovascular complication, 17% of enrollees had obesity, 74% had hypertension or were taking blood pressure lowering medication, 16% had hypertriglyceridemia or were taking a fibrate and 11% had low HDL-c.
The study results found independent associations between micro and macrovascular complications and hypertension, low HDL-c and the number of risk factor abnormalities present. Surprisingly, glycemia assessed by HbA1C in this study was not associated with complications; this doesn’t mean that HbA1C control is not important, it just suggests that when HbA1C is addressed, blood pressure may emerge as a dominant risk factor. The study findings reported that high blood pressure may in fact, be associated with all complications, and low HDL-c with neuropathy and macrovascular disease. Elevated BMI and triglycerides showed no independent associations and are not extremely strong risk factors in people with type 1 diabetes; however, increased adiposity can lead to increase in the risk of complications.
In conclusion, the findings of this study indicate that more intensive management of risk factors such as hypertension, adiposity and lipid profile in people with type 1 diabetes is beneficial in reducing type 1 diabetes complications. In other words, this suggests that a focus on more intensive management of risk factors, other than glycaemia may be beneficial in routine clinical management of type 1 diabetes, as there are associations between blood pressure and lipid risk factors and prevalent micro and macrovascular disease.
- Hyperglycemia is highly associated with micro and macrovascular complications in type 1 diabetes. However, despite intensive glycemic control, the risk of complications in people with type 1 diabetes still remains high.
- Other factors, such as blood pressure, adiposity and lipid profile, in the context of routine clinical practice, have a significant role in the risk of complications such as worse cardiovascular outcomes, neuropathy, etc.
- More intensive management of risk factors other than HbA1C alone is beneficial in reducing type 1 diabetes complications.
Bhattarai S, Godsland IF, Misra S, et al. Metabolic health and vascular complications in type 1 diabetes. Journal of Diabetes and Its Complications. https://doi.org/10.1016/j.jdiacomp.2019.05.026
Marian Ayad, BSPharm, BCPS, PharmD candidate, University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences.