HYPERTENSION

Type 1 Diabetes

  • In the absence of persistent nephropathy (microalbuminuria or proteinuria), the prevalence of hypertension in Type 1 diabetes is similar to in non-diabetic individuals

  • Blood pressure rises as microalbuminuria becomes established

 

Type 2 Diabetes

  • 40-50% of patients with Type 2 diabetes have hypertension at the time of diagnosis
  • Hypertension accelerates cardiovascular disease and the decline in renal function in established nephropathy

 

MANAGEMENT

 

Confirm the Diagnosis

  • If hypertension is severe (DBP >110mmHg) and there is evidence of Grade III-IV retinopathy, start anti-hypertensive therapy immediately
  • If hypertension is sustained or severe (DBP >110mmHg), there is target organ damage retinopathy, nephropathy, LVH) present, or there are multiple cardiovascular factors, institute therapy within 1 - 2 weeks
  • In uncomplicated patients (no target organ damage, BP <150/90mmHg), delay pharmacological intervention and reassess after 12 weeks of lifestyle measures
  • All patients with Hypertension should receive lifestyle advice
  • British Hypertension Society guidelines for hypertension management 2004 (BHS-IV): summary. Br Med J 2004; 328; 634-640. Free fulltext available at       www.bhsoc.org/pdfs/Summary%20Guidelines%202004.pdf

 

Thresholds and Targets  

  • The usual threshold for anti-hypertensive therapy is BP>140/90 mmHg

  • The target BP is < 130/80mmHg in the absence of nephropathy
  • In patients with nephropathy, and Type 1 diabetes a target BP of <120/70mmHg is recommended.

 

Treatment in absence of Microalbuminuria or Proteinuria  

  • ACE inhibitors, angiotensin receptor blockers (ARBs), b-blockers, thiazide diuretics, calcium channel blockers and a-blockers are all effective in lowering blood pressure

  • The British Hypertension Society "ACD" rule helps in selecting initial therapy

  • Polypharmacy is likely: 30% will require three or more drugs to achieve target BP; fewer than half will be controlled by monotherapy

  • An interval of at least four weeks should be allowed to observe response after any change in therapy, unless it is necessary to lower BP more urgently

  • Sub-maximal doses of two drugs result in larger BP responses and fewer adverse effects than maximal doses of a single drug

  • Select drugs with once (or maximum twice) daily dosage to improve adherence

  • ACE inhibitor should usually be included in treatment "cocktail"

  • ARBs are a useful alternative particularly in the presence of ACE inhibitor cough

  •  Bendroflumethiazide should not be titrated beyond 2.5mg

  • Check comparative drug costs within each class: refer to Tayside Area Prescribing Guide and British National Formulary

  • Where no cost disadvantages, fixed dose combinations are useful to reduce the number of medications prescribed, providing the individual preparations have been tolerated.

  • Combination of thiazide and b-blocker may lead to a clinically important deterioration in glycaemia control and should be avoided unless risks thought to be outweighed by benefit.

 

The “ABCD” (ACE inhibitor,Beta-blocker, Calcium antagonist, Diuretic) rule referred to in the 2004 British Hypertension Society guidelines has been superceded by  “ACD” rule following several lines of evidence suggesting that beta-blockers and diuretics in combination can promote the development of type 2 diabetes. See weblink below for updated slide on BHS website www.bhsoc.org/docs/BP%20Algorithm%202%20BW.ppt.

 

Treatment in presence of Microalbuminuria or Proteinuria  

  • Anti-hypertensive therapy reduces urinary albumin excretion and delays progressive loss of glomerular function. The greatest renal benefits have been observed in trials with ACE inhibitors in type 1 diabetes and ARBs in type 2 diabetes.
  • Other classes of drugs may be added as required to achieve target BP.
  • Short acting dihydropyridine calcium channel blockers (e.g. nifedipine), are not as effective in limiting protein excretion and should be avoided.

 

Indications for Hospital Referral  

 

Use of ACE Inhibitors/Angiotensin Receptor Blockers: safety  

  • Consider the presence of renal artery stenosis in patients with type 2 diabetes
  • Suspect underlying renovascular disease if widespread atheroma present (e.g. carotid or abdominal bruits, aortic aneurysm, absent peripheral pulses)
  • Before starting ACE inhibitor or ARB, measure baseline urea, creatinine and electrolytes
  • Repeat after 4 - 7 days, again after 1 month and thereafter annually
  • Stop drug if significant hypotension or a significant rise in creatinine occurs (>20% from baseline)
  • ARBs should NOT usually be used in combination with ACE inhibitor therapy except in certain specialist settings (e.g. renal or renal diabetes clinic)
  •  Renin inhibitors are promising new agents which may be suitable for patients intolerant of ACE inhibitors and ARBs; they are being assessed for suitability in combination therapy with ACE inhibitors and ARBs (monitor potassium for hyperkalaemia)

 

N.B Ambulatory Blood Pressure Monitoring (ABPM)  

  • When ABPM is used, mean daytime BP and not over the whole 24 hours should be used to make treatment decisions
  • BP measured by ABPM is systematically lower than surgery or clinic measurements in hypertension patients; the average difference in techniques is 12/7 mmHg
  • Outcome trials in hypertension have all been based on surgery or clinic BP measurement, not on ABPM data
  • Serial routine BP measurements (whether in primary or secondary care) accessed via SCI-DC may obviate the need for ABPM in some cases

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FLOWCHART FOR MANAGEMENT OF DYSLIPIDAEMIA IN DIABETES

FLOWCHART FOR MANAGEMENT OF DYSLIPIDAEMIA IN DIABETES

 

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LIPID LOWERING - Age Considerations

Age Limits

  • For secondary prevention, the upper age limit for initiating lipid lowering drugs is 75 years
  • For primary prevention, the upper age limit for initiating therapy is 70 years
  • Once treatment is established, it should not be discontinued at any particular age

In patients with persistently raised Triglyceride concentrations

  • Check fasting sample (Total-cholesterol, HDL-cholesterol & Triglycerides)
  • Optimise glycaemic control
  • Exclude co-existing pathology e.g. alcohol-related liver disease

 

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LIPID LOWERING - DRUGS

Drug choice should be made on the balance of trial evidence, safety and cost-effectiveness

Statins

  • First-line choice for isolated hypercholesterolaemia or combined hyperlipidaemia, providing (random) triglycerides are < 5 mmol/l.
  • Monitoring of liver function and creatinine kinase is recommended

Fibrates

  • Suitable if combined hyperlipidaemia present (random triglycerides > 5 mmol/L)
  • Not advisable in the presence of renal impairment (serum creatinine > 150 µmol/l)
  • Combination therapy with a Statin is possible, but close monitoring of liver function and creatinine kinase is essential (increased risk of hepatic damage and myositis)

 

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