Adverse Effects of Statin Therapy: Perception vs the Evidence
Eur Heart J 2018 Apr 27; F Mach, KK Ray, O Wiklund, et al 

This paper in European Heart Journal summarises the evidence regarding the safety of statins from randomised clinical trials and genetic studies published from 2000 to 2017. The authors specifically assessed the evidence for the risk of diabetes, cognitive decline, renal impairment, deterioration of liver function, cataracts, and the risk of hemorrhagic stroke associated with long-term statin therapy. The conclusions are as follows:

Diabetes 

Statins increase the risk of the onset of diabetes at a rate of approximately 1 case per 1000 patients per year of treatment, but at the same time, statins prevent about 5 cardiovascular events per 1000 patients. The risk of new-onset diabetes is highest in the patients with pre-statin risk factors for diabetes.

Cognitive function

Statin treatment and very low LDL-cholesterol levels from other cholesterol treatment do not affect cognitive function.

Renal function

Statins do not reduce renal function and may actually protect the kidneys, but this possibility requires further research.

Hepatic function

Mild increases in ALT (alanine aminotransferase) occur in patients on statins, but on their own, this is not a reflection of clinically significant disease. Clinically significant liver injury can occur with statins, but this is extremely rare. Routine monitoring of liver enzymes is not necessary or clinically justified.

Hemorrhagic stroke

Statins reduce the risk of first and subsequent ischaemic strokes but may produce a slight increase in haemorrhagic stroke in individuals with prior stroke.

Cataracts

Statins do not increase the risk of a cataract.

The researchers conclude that statins are very safe, and the small risks described above do not outweigh the significant cardiovascular benefits that patients receive from these drugs. I am sure that this is not the end of the discussion about statins, and it's probably preaching to the converted. However, the evidence is clear; statins in appropriate indications save lives and concerns about potential side effects are in most cases misplaced.