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Managing Clinical Problems in Diabetes, Case Study #10: Osteomyelitis

Edited by Trisha Dunning AM, RN, MEd, PhD, CDE, FRCNA and Glenn Ward MBBS, BSc, DPhil (Oxon), FRACP, FRCPath

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Mrs. PJ was referred to the diabetes centre by a physician in the infectious diseases department of a large metropolitan hospital. Mrs. PJ is an 80-year-old woman who has had type 1 diabetes for 54 years. She lives with her son, who is single. Her son draws up her insulin in a syringe and Mrs. PJ administers it herself. Mrs. PJ had a hypo while she was attending the infectious diseases clinic and was referred to you for education about hypoglycemia….

As you discuss the hypo episode with her, you discover she has frequent hypoglycemic episodes and no longer recognizes hypoglycemic symptoms. She tells you her blood glucose levels change rapidly, which she finds frustrating. 

She has osteomyelitis of the left heel, which is why she is attending the infectious diseases clinic. You note in her medical record that she has chronic renal impairment (creatinine 295, normal 50–100). 

She has had a recent presentation to the emergency department with unstable angina refractory to anginine and has a past history of non-ST elevation myocardial infarction (NSTEMI). 

The medical notes indicate she was ‘Given isolated, extra doses of actrapid according to the blood glucose’ while in emergency. Her son reports he gives an extra dose of Actrapid whenever Mrs. PJ’s blood glucose is > 226mg/dL(12 mmol/L). 

Current medications

  • Aspirin 100 mg/day
  • Atorvastatin 40 mg hs
  • Caltrate 1 tablet/day
  • Calcitriol 1 tablet am
  • Omeprazole 20 mg/day
  • Diltiazem 60 mg BD
  • Paracetamol QID (strict)
  • Ciprofloxacin 500 mg BD
  • Augmentin BD
  • Furosemide 200 mg
  • Spironolactone 12.5 mg/day
  • NPH (Protaphane) 24 units am
  • Novolog 3-5 units am but the son gives extra Novolog at home when the blood glucose goes above 180mg/dL.(10 mmol/L)
  • Glyceryl trinitrate patch 10 mg
  • Metoprolol 100 mg mane

 

Diabetes educator

I would ascertain her latest HbA1c, or order one if there was no recent result: 54 years of type 1 diabetes means 54 years of hypoglycemia. However, with recent new insulins now available, this scenario can be changed. Neither Novolog nor NPH are the insulins of choice. Both are extremely variable with respect to when their actions start, when they peak, and how long they last. Novolog peaks 4 hours after administration, which for most people means just before lunch. People with diabetes who are prescribed Novolog must eat a snack within 3 hours of administering this insulin and can rarely afford to prolong the time they have their lunch or evening meal. When administering Novolog with the evening meal, a significant supper is also required to prevent hypoglycemia. 

NPH generally starts to work within 2 hours of administration and can peak in its action anywhere from 4-12 hours. This means that later in the afternoon, Mrs. PJ could in fact be having her lunchtime Novolog and her breakfast NPH peaking at the same time, creating a profound hypoglycemic effect. It is also important to note that the entire regimen appears quite unusual. People with type 1 diabetes often take NPH at bedtime, rather than in the morning. At present Mrs. PJ has no overnight insulin and could be starting each day with raised blood glucose levels. This could also be affecting her sleeping patterns if overnight hyperglycemia and subsequent polyuria is causing her to use the toilet frequently overnight. 

Waking with raised blood glucose levels may in turn be giving a false impression of her actual glycemic control and insulin requirements and therefore means that much larger doses of insulin are administered in the morning to ‘try to catch up’ with morning hyperglycemia. 

There are also several other considerations. How many extra doses of Novolog is Mrs. PJ giving herself? When is she monitoring her blood glucose levels and does this coincide with the peak action of her insulin? For example, if following breakfast Novolog, Mrs. PJ tests her blood glucose levels and they are above 216mg/dL(12 mmol/L), does she administer herself more insulin? This is potentially very dangerous and also helps to explain why sliding scales of Novolog will never achieve good and safe glycemic control. The peak action time of Novolog is usually 4 hours after administration; taking a blood glucose level only 2 hours after means that the peak action of Novolog has not yet occurred. Giving extra Novolog at this time markedly increases the risk of hypoglycemia occurring. 

Another consideration is that she is being treated for osteomyelitis. Infection usually causes a marked rise in blood glucose levels. More insulin is often required to address infection-induced hyperglycemia. Mrs. PJ’s osteomyelitis may now be resolving and therefore her insulin requirements will need to be reduced. It would also be useful to identify whether other infections were present, for example a urinary tract infection where symptoms of polyuria may be masked due to hyperglycemia and diuretic therapy and thrush resulting from current antibiotic treatment. 

There is no mention of her level of cognition. Performing a Mini-Mental State Examination (MMSE) is imperative to determine the level of understanding she has and the degree of insight into her condition. Vascular dementia is a long-term complication of diabetes and she already exhibits other vascular complications: NSTEMI and chronic renal failure. 

I would change Mrs. PJ to a basal analog and bolus analog. Lantus at breakfast should provide 24 hours coverage as the basal insulin and markedly reduce any nocturnal hypoglycaemia. Daily glargine in older people is associated with fewer hypoglycemic episodes and improvements in blood glucose control (Janka et al. 2005). Novolog or Humalog insulin with each meal can provide more timely coverage of postprandial excursions in blood glucose control, reduce the need to snack between meals and provide more flexibility with meal times. 

A short hospital admission may be useful to carefully monitor insulin regimen changes. Self-insulin administration could be observed, sites of injections could be examined for hypertrophy and hypoglycemic management in terms of treatment and prevention could be revised. Such a short admission could also bring a much-needed team approach:

  • an endocrinologist to review insulin regimens;
  • the diabetes educator to review knowledge and self-management skills;
  • the dietitian to maximize nutritional intake for an older woman with chronic renal failure;
  • the podiatrist to ensure modified footwear can be fitted to assist with wound healing and minimize wound breakdown; and
  • a social worker to review Mrs. PJ’s home situation and identify any services she may need such as Meals on Wheels. 

Osteomyelitis is a very difficult and challenging infection to treat and a course of intravenous antibiotics may prove a more useful intervention.  

Time and resources must also be devoted to Mrs. PJ’s son to determine his level of understanding pertaining to his mother’s diabetes and management. It would appear that he might have been following the emergency department intervention strategy of a sliding scale regimen. It is also important to identify whether anyone actually instructed him to use a sliding scale when his mother was discharged. This scenario is unfortunately common — medical and nursing staff do not always fully understand diabetes and its management and provide instructions that can then create the type of scenario we are now confronted with. 

Her other medications need to be reviewed as follows:

  • Atorvastatin needs to be monitored carefully in an 80-year-old with chronic renal failure. Both renal function and creatine kinase (CK) need to be measured regularly. There may be now little benefit to remain on this medication, or it may need to be reduced to a lower dose.
  • Caltrate should be ceased as it is a contraindication when prescribed calcitriol. This is even more relevant in a frail older woman with chronic renal failure.
  • Furosemide is ordered at night and I would question how an older woman is expected to sleep if she must get up to void frequently.
  • Spironolactone may require to be reconsidered with respect to a frail older woman with poorly controlled type 1 diabetes due to a high risk of hyperkalaemia, respiratory or metabolic acidosis.
  • Metoprolol may have a role in masking the symptoms of hypoglycemia.

In conclusion, the management of older people with diabetes should be a team effort (Tattersall 1997).

 
Diabetes educator 2 

I agree with this comprehensive assessment. Managing diabetes in older people is a complex and changing undertaking. Mrs. PJ is 80; management needs to consider her life expectancy and prioritize her health risks and preferences. She may prefer to maintain her independence, which may be a key aspect of quality of life for her. The MMSE may or may not be helpful, depending on the conditions under which it is undertaken. If it occurs under ‘idealized in hospital, she may perform well and be judged capable of self-care. However, if it was performed under ‘usual’ conditions such as at home a different result may be obtained. Serial MMSE tests may be more useful than a single test. It would also be important to undertake other activities of daily living (ADL) tests and these should also be performed at regular intervals. Mrs. PJ’s and her son’s knowledge of diabetes and its management and insulin technique may need to be checked. 

Her nutritional status needs to be considered and she may benefit from supplements to improve her wound healing capacity and overall health. If possible, the mental status of both Mrs. PJ and her son should be assessed. Managing diabetes is a considerable burden and one or both may be suffering from depression. The focus is currently on her foot with the cellulitic heel. It is essential that both feet are monitored: it is not uncommon for the non-damaged foot to be neglected.

 
Podiatrist 

Osteomyelitis of the heel has a poor prognosis. Mrs. PJ’s advanced age and the presence of renal disease suggest she has peripheral vascular disease, which will impair healing and reduce the effectiveness of systemic antibiotics. If not already undertaken, a thorough assessment should include palpating her pedal pulses. If they are weak or absent, an ankle brachial index followed by a duplex scan (if her arteries are calcified) will provide more information about her vascular status. If these tests indicate that Mrs. PJ has peripheral arterial disease, she should be reviewed by a vascular specialist to determine whether revascularisation is possible to improve her blood supply and her healing potential. 

While the infectious disease department is monitoring her antibiotic therapy, foot disease usually requires a multidisciplinary approach including debridement, wound care and pressure offloading. The degree of debridement required depends on the blood supply and extent of the necrosis. It may be performed by a podiatrist with expertise managing diabetic foot pathology or in an operating theatre by a vascular or orthopedic surgeon if extensive debridement is indicated.

Wound care should include non-occlusive dressings changed every three days to control exudate, prevent maceration of the wound margin and maintain a slightly moist environment. However, if she has very poor circulation, non-adherent dry dressings are preferred. Pressure on the wound should be alleviated using in-bed appliances such as a foam tunnel to keep her heel off the bed. When walking, a specially padded healing shoe or a shoe with the heel cut away to reduce pressure on the heel is essential. Careful monitoring of the size, depth and appearance of the wound and underlying bony changes using X-rays is important. Surgical resection of the bone may be required if the osteomyelitis does not respond to antibiotics and the pressure and wound management strategies outlined.

 

The aims of the book are to: (1) address commonly encountered diabetes management problems; (2) develop comprehensive responses from a range of relevant health professionals who suggest management approaches relevant to their area of practice. The specific health professionals who provide comments about each case depend on the specific clinical issue; and (3) stimulate thought and discussion. 

The target readership is health professionals from a range of professional backgrounds and general as well as specialist professionals such as general practitioners, nurses, dietitians, and podiatrists. The book will be particularly useful for beginner practitioners specializing in diabetes. In addition, it will provide suggestions or food for thought for more experienced practitioners. The cases will be excerpts from the book are all real and are presented exactly as the information was received from the person making the referral. General practitioners, diabetes educators and people with diabetes referred most of the cases; some were self-referrals by people with diabetes. They represent referrals to various diabetic health professionals and concern commonly encountered clinical issues.

Next Week: Another Case Discussion

For more information on the book, just follow this link to Amazon.com, Managing Clinical Problems in Diabetesalt

Copyright © 2008 by Blackwell Publishing Ltd, UK

Edited by Trisha Dunning AM, RN, MEd, PhD, CDE, FRCNA and Glenn Ward MBBS, BSc, DPhil (Oxon), FRACP, FRCPath