Glycaemic control and mortality in older people with type 2 diabetes: The Fremantle Diabetes Study Phase II.
AIM
To investigate whether tight glycaemic control achieved with metformin, insulin or sulphonylurea-based pharmacotherapy increases all-cause mortality in older people with type 2 diabetes.


MATERIALS AND METHODS
We conducted a prospective cohort study of individuals with known diabetes recruited between 2008 and 2011 and followed until 2016. The impact of baseline glycated haemoglobin (HbA1c) on mortality hazards was investigated in participants aged ≥75 years. Proportional hazards models for time to death were constructed from the baseline clinical assessment, then the variables of interest (HbA1c, treatment category and their interactions) were entered.


RESULTS
There were 367 participants (mean age 80.1 ± 3.9 years, median [interquartile range] HbA1c 50 [45-56] mmol/mol or 6.7 [6.3-7.3]%) who were followed for a median (interquartile range) 6.7 (4.5-7.7) years, during which 40.9% of the participants died. At baseline, 60.4% were on metformin-based treatment, 35.3% on sulphonylurea-based treatment and 23.2% on treatment including insulin. Baseline HbA1c was significantly associated with mortality in a model that included interactions between HbA1c and the three treatment-based groups compared with non-pharmacological treatment. The metformin treatment group had higher mortality when HbA1c levels were <48 mmol/mol (<6.5%) and the sulphonylurea and insulin treatment groups had higher mortality when HbA1c levels were <52 mmol/mol (<7.0%), with hazard ratios of 2.63 (95% confidence interval [CI] 1.39-4.97), 2.49 (95% CI 1.14-5.44) and 2.22 (95% CI 1.12-4.43), respectively.


CONCLUSIONS
Tight glycaemic control may be hazardous in older people with type 2 diabetes when achieved with pharmacotherapy with metformin, and especially with insulin or sulphonylureas. These data confirm that overtreatment is likely to be an important clinical problem in this vulnerable population.
['Bruce|David G|DG|0000-0002-9979-6867', 'Davis|Wendy A|WA|', 'Davis|Timothy M E|TME|0000-0003-0749-7411']
D000368:Aged D000369:Aged, 80 and over D001786:Blood Glucose D003924:Diabetes Mellitus, Type 2 D004359:Drug Therapy, Combination D005260:Female D006442:Glycated Hemoglobin A D006801:Humans D007004:Hypoglycemic Agents D007328:Insulin D008297:Male D008687:Metformin D016016:Proportional Hazards Models D011446:Prospective Studies D013453:Sulfonylurea Compounds D016896:Treatment Outcome
glycaemic control type 2 diabetes metformin cohort study sulphonylureas insulin therapy